Spare Parts (audio story)

 was the thirty-fourth story in Big Finish's monthly range. It was written by Marc Platt and featured Peter Davison as the Fifth Doctor and Sarah Sutton as Nyssa.

It explained the somewhat surprising origins of the Mondasian Cybermen. It was the partial inspiration for two 2006 Doctor Who television episodes — The Age of Steel and Rise of the Cybermen, on which Spare Parts writer Marc Platt received acknowledgement.

The origins of the Cybermen was also explored in the 2017 two-part story World Enough and Time and The Doctor Falls, which uses the original Mondasian Cybermen from Spare Parts and also makes reference to this story and the Doctor Who Magazine comic strip The World Shapers as the Twelfth Doctor tells the two incarnations of the Master on the multiple origins of the Cybermen.

Publisher's summary
"I'm not even sure they are people by the end. They're just so many tinned left-overs..."

On a dark frozen planet where no planet should be, in a doomed city with a sky of stone, the last denizens of Earth's long-lost twin will pay any price to survive, even if the laser scalpels cost them their love and hate and humanity.

And in the Mat-infested streets, round about tea-time, the Fifth Doctor and Nyssa unearth a black market in secondhand body parts and run the gauntlet of augmented police and their augmented horses.

And just between the tram stop and the picture house, the Doctor's worst suspicions are finally confirmed: the Cybermen have only just begun, and the Doctor will be, just as he always has been, their saviour...

Surfacing (1)
1950s-style newsreel footage crackles across the airways explaining that it's been 6 years since anyone stepped onto the surface of the planet. A voice from the Central Committee wishes astronaut Philpott good luck as he steps from the capsule. We hear heavy breathing as he steps out of the rocket. His breathing becomes more laboured, he screams and is killed.

Nyssa reads the marquee on the top of a picture house. The Doctor explains that that film sounds particularly tawdry. He notices that the cinema has been boarded up for years. Nyssa replies that a boarded up picture house doesn't prove that they've landed on Earth. The Doctor tells her that coming here was probably not a good idea and she replies that the Doctor didn't say much at all, just that the coordinates weren't right. Nyssa determines that they haven't landed on Earth, but the Doctor refuses to tell her where they have landed. The streets are empty and the atmosphere is stuffy, like a hothouse. The Doctor tries to convince her that have they landed in the heart of London in the 1950s, but she knows that cities on Earth weren't built into stone caverns and that Earth isn't a grey planet drifting light years from any star. The Doctor knows that he's not on Earth and tells Nyssa that they should leave, but convinces himself to explore for a half hour and then meet back at the TARDIS. They split up; he tells Nyssa to explore but not get involved.

Mr Hartley and his daughter Yvonne chase a Deluxe Mark VI Cybermat under a timber stack. Dad tries to catch it but it turns out there's a swarm of them. The timbers fall on him, crushing his chest. Yvonne calls for help as Nyssa comes up to see what's wrong. Yvonne coughs, telling Nyssa that she needs her pills, which she takes. Together they lift the timbers off Mr Hartley and pull him out, but he doesn't appear to be moving. Nyssa checks and notices that he's not breathing and doesn't have a pulse. She thinks he's dead. Mr Hartley pops up, stating he's fine except for his arm. Nyssa has gotten dust on her clothes and being so close to lights out, they insist that she come back to their house to be cleaned up. She argues, stating she has to meet someone but follows the two back to the house.

The Doctor explores and finds a shop that is closed for the night. The owner of the shop walks out, telling him that he won't be able to do much exploring since it's close to lights out. When the Doctor introduces himself, the man asks if he is in public or private practice and asks for identity papers and ration book, both of which the Doctor says he's lost. The man notices that the Doctor does not have any transplants and that he appears very healthy. The Doctor states he thought artificial organs were all the rage. The man mentions the Committee and their new gadgetry, but there is still a waiting list for natural transplants. Reading the sign over the shop, the Doctor determines the man is Thomas Dodd, "purveyor and fitter of necessary bodily parts". The Doctor asks Dodd to tell him about the city. Thomas invites the Doctor inside for a drink to talk about it.

Mr Hartley and Yvonne take Nyssa back to their home. As they enter, Yvonne spots Sisterman Constant in the living room. Her brother, Frank Hartley, walks in saying the Sisterman's been waiting for them. Frank asks who Nyssa is, she introduces herself and Mr Hartley says she missed the last tram home and they invited her in. The Sisterman asks if she knows Nyssa, who Mr Hartley tells her is from the South District and out of her jurisdiction. Constant then asks how Yvonne is feeling and if her medication is working, and asks Mr Hartley how he is after his cardioectomy. He says normal except he can feel the paddles moving in the chest unit. She notices his arm and Mr Hartley says it's nothing, saying he doesn't want or can afford to replace it. Sisterman asks for Nyssa's last name, which she gives as "of Traken", and asks for identification papers. Nyssa tells Sisterman Constant off and she heads out of the apartment. Frank asks about "a call up" and Sisterman tells him he's too young. Nyssa still wishes to leave, but the family won't let her go telling her it still isn't safe after dark in the city.

Constant makes a phone call, telling whoever is on the other end that she has a selected at the Hartley's address and reports a stranger at the same address. She also advises that patrols be on the lookout for any other "unregistered strangers".

Dodd sits down, pouring himself a drink and asking (again) if the Doctor would like one. The Doctor asks the population of the city, which Dodd replies is down to a few thousand. The Doctor then asks if this is the last inhabited city on Mondas. Dodd thinks he's crazy, but the Doctor has one of his questions answered. He leaves Dodd's shop and heads back towards the TARDIS, with Dodd in pursuit. As he walks, he meets a police officer on horseback who tells him to stop. The officer tells them to identify themselves, as civilian movement is restricted. The Doctor notices that the Cyberman doesn't have the blank mask yet and still human except for some augmented bodywork and not advanced as he thought. The Cyberman whips him, knocking him down. He demands his identification papers to which the Doctor replies that he doesn't have an identity to them, not yet at least. As the officer is questioning him, the Doctor pulls out a Chinese Cracker and matches, lighting it and startling the horse. Dodd and the Doctor run as the Cyberman calls for assistance.

Nyssa is clearing the table from dinner as Frank truants his sister about her friend Eric Krailford. Mr Hartley tells Frank to go do his homework. Yvonne whistles to her trilby mat 2, a cybernetic bird. Mr Hartley asks Nyssa if she could fix his chest box. As she works on it, the family hears a noise outside their apartment. Mr Hartley tells Frank to turn on the television to drown out the sound. Their neighbour, Mrs Ginsburg, is taken by the police. Nyssa tries to help but notices the windows are all boarded up. A moment later, they hear a large number of patrol vehicles driving through the streets. They all ignore it, saying they don't want to get involved and begin to talk about the holiday decorations they have to put up.

The Doctor hears the patrols pass by and confronts Dodd for following him. They notice a mechanical digger passing by on a truck and Dodd tells the Doctor that whole areas of the city have been blocked off. Dodd says it's for the new parade ground. The Doctor suggests they take a look and head towards the old abandoned church.

Mr Hartley takes a raggedy old tree out and the family begins to pull out the decorations to go on it, including a big star. Yvonne asks if Nyssa has a posh tree at her house and Nyssa tells her about an autumn festival where the people wind up pelting each other with fruit. Yvonne says there are no more trees, except where she works at the hydra house. Nyssa is worried about the old woman who was taken. Yvonne tells her that the Committee does what they think is best. As they move the box of decorations, Yvonne's pet Cybermat who she calls Matti appears. Nyssa is confused as to what it is. Matti doesn't come when Yvonne calls it and Nyssa offers to take a look at it.

The Doctor and Dodd climb the stairs to the top of the bell tower. Dodd tells him you could see the entire city before the church was abandoned. The Doctor replies that all the old temples of worship, the church and the picture house, closing. Dodd thinks the patrols are levelling the area around the city for a new parade grounds. The Doctor replies that they're not touching the buildings. Dodd notices that the patrols are digging up the graveyards. As they talk, a Cyberman comes up the stairs telling the two men not to move; they are escapees and required for adjudication.

Frank complains that Nyssa didn't touch her dinner and they've now wasted all their rations for the holiday. He tells his Dad that the work crews are on the verge of breaking through the city to get to the planet surface, but Mr Hartley thinks that's a long way off...if ever. Frank tells Mr Hartley that he wants to join the work crews. He refuses to let him join as he's too young and he'd never come back from the crews, continuing that no one's ever come back. Yvonne begins coughing again. Frank yells about giving away their rations and storms out of the house. Yvonne takes her pills and the coughing stops. Nyssa insists that she leaves and will bring back food for the Hartley's. Suddenly, there's banging outside the house. Mr Hartley tells Yvonne to take Nyssa to the back room and he'll hold them off as long as he can.

The Cyberman tells the Doctor and Dodd that the bell tower is restricted to civilians. The Doctor questions why, but the Cyberman tells them they are recognised criminals required by adjudication by the Committee. The two overpower the Cyberman and use the bell ropes to make the church bell ring. The Doctor asks Dodd if he has thought about the future of the city saying it is headed for extinction. He tells Dodd that the Cybermen are the future and that he may not be able to stop it, but he can give the city a wakeup call. The church bells ring loudly through the city as he tells Dodd he can help stop the horror of the Cybermen.

Patrols enter the Hartley apartment, pushing his way past Mr Hartley. Yvonne gives Nyssa her Cybermat and helps her slip out the back door and into the alley as the Cybermen begin their search. Frank tells the patrols that Nyssa is in the back room, but she's already gone. Mr Hartley hears the bells in the church tower ring and the family goes out into the streets to investigate. Yvonne asks if it's a warning.

The Doctor pushes past the crowd and finds Nyssa in the square. The two enter the TARDIS. Nyssa questions the Doctor, telling him that the planet isn't Earth. The Doctor replies that it isn't, but had to make sure it was the planet he thought it was before they leave. Nyssa now knows that this is Mondas and the people here are destined to become the Cybermen. The Doctor explains that they can't interfere but the bell is a wake-up call so the people can see what's happening and can stop it before it's too late. He tells Nyssa that the people have to change the future, they can't do it.

Cyber Commander Zheng sends a message stating police patrols have reported a disturbance in the city and that hostile intruders have been observed. An electronic noise replies through his communicator. The Committee replies telling him that the insurgency must be crushed and the intruders found and eliminated immediately.

Necessary Force (2)
The Doctor tells Nyssa that the people of Mondas must decide the future for themselves. She tells him that they're good people and they're suffering and if he won't stay to help, she will. Nyssa then tells him that she wants to stop the Cyberman from coming into being. The Doctor explains that if she stops one history, it will just be replaced with another, possibly just as bad.

As they talk, their conversation is being monitored.

The Doctor continues on about becoming involved, how sometimes you do and sometimes you don't. Nyssa tells him that he should have thought of that when it came to sacrificing Adric. He feels terrible about that and Nyssa heads back to collect her things.

Crowds are still gathered near the church. The police attempt to disburse them but they yell at them about digging up the graveyards. Sisterman Constant arrives and is told that the Committee advises force may be necessary to disperse the crowd. The bells stop and troops are sent in with whips to move the crowd out of the area.

Nyssa comes back to the control room and apologises for how she acted, including about Adric. The Doctor replies that they never had a chance to mourn him. Nyssa says that she just wants to take the Hartleys some food and provisions. She tells him that everything is rationed by the Committee. The Doctor says that are signs of cybertechnology everywhere, including the police. Nyssa goes to show the Doctor the Cybermat that Yvonne gave her but it's gone. He screams at her for bringing that into the TARDIS.

Doctorman Allan calls for a nurse to come to one of the operating rooms. A Cyberman is having problems with his pulmonary unit rejecting. She tries but is unable to save him. Sisterman Constant comes in and notices two Cybermen have died. Allan tells her that is the third one back from the surface and that the processing won't stabilise. Allan pours herself a drink and offers one to Constant, who refuses. She says her staff is exhausted, working all hours with no resources but the Committee just wants more people processed. Allan wants to stop all conversions and rethink the processing. Sisterman Constant relates the story of the riot in the city to Allen who laughs and continues drinking. She thinks they should call off digging up the graveyard as if dead bones would help. Constant talks about Nyssa to Doctorman Allen who is then suddenly called to appear before the Committee. She can't understand how strangers could even exist. Constant storms off after being tempted by Allen with a glass of wine. Doctorman Allen calls the switchboard, asking to be transferred to the surveillance department.

The Doctor and Nyssa continue to search for the Cybermat. Alarms sound and they run to the TARDIS control room to find the console on fire. The Doctor quickly puts it out but discovers an energy leak that could cause the TARDIS to explode. Nyssa stops it by hitting the isolator failsafe. They open the console and find the Cybermat destroyed; it chewed into the energy conduit. Nyssa volunteers to repair the damage and the Doctor heads out for some fresh air.

Doctorman Allan is contacted by the Committee who tells her that resources are low and soon life will be unsustainable in the city. She scolds them by saying they mean "Human Life". The Committee tells her that she must work faster. She replies by saying that the staff is overworked and the death rate is increasing on the work crews. The Committee offers more resources but Allan says that old bones won't work. They say that processing will be increased. Doctorman Allan wants more time to find a solution. The Committee discusses it and disagrees. They decide that the city uses too many vital resources and will be shut down. Allen calls them insane and wants to know what could be more important than saving the people. The Committee answers, "We must survive".

The Doctor steps out of the TARDIS and finds another Cybermat. He tries to get it away from the door when Frank shows up. He tells the Doctor that is a Mark XII surveillance model and that the Committee uses them. He introduces himself and meets Frank, who he thanks for looking after Nyssa earlier. Frank tells the Doctor that the police came by to look for her which upsets the Doctor. The Doctor opens the door, telling Frank he can find Nyssa inside the TARDIS and to inform her he has a call to make. Frank steps in and soon tells Nyssa about the visit from the police. He then shows her a piece of paper saying Yvonne is being called up to the work crews and she's left already. Mr Hartley sent Frank to find Nyssa. She tries to console Frank but he is angry that she got the notice and not him.

The Committee discusses if Doctorman Allan understands her task. They say she still has an illogical mind. The Committee thinks that the riot in the city was started by the strangers and that they have one of them under observation.

The Doctor is under observation through the Cybermat by Doctorman Allan. The Doctor wants to head back to Thomas Dodd's shop but he has no money for the tram. Constant knocks on Allan's door and is offered a drink, which she again refuses. Constant tells her there are recruits waiting for processing. Constant asks how the meeting with The Committee went. Allan replies that processing quotas are to be updated and eventually it'll be processing for everyone. She tells Constant that no one will be exempt. Constant runs off to tell the other Sistermen about the new quotas. Doctorman Allan decides its time to get a better look at our stranger.

The Doctor runs after a truck flagging it down, saying they're dropping cargo all over the road. The Cyberman exits the truck and recognises the Doctor. He takes the Cyberman to the back of the truck, again saying the cargo is all over the road. When the Cyberman disagrees, the Doctor loosens the ropes causing the bones to fall on top of him, then takes the truck and drives away. The Cyberman calls in a report that he has found the intruder and is driving off.

Nyssa and Frank are in the TARDIS still working on repairs. She tells Frank that the Cybermat destroyed the console. He says it's the energy that attracts them. Nyssa continues sealing the cables. She asks Frank if the call up involves some kind of processing. He says it's augmentation. They hear a noise and turning the viewer on, Nyssa and Frank see a swarm of Cybermats heading towards the TARDIS.

Sisterman Constant walks up and down the lines of recruits for processing. Doctorman Allan leaves her in charge, as she has an errand to run. As she walks, Constant sees Yvonne. She asks Constant when she gets her uniform, as she wanted her Dad to see her before she left. Allan leaves as Constant continues walking down the line of recruits.

The Committee decides that the city is a drain on resources and must be shut down so they can survive. They decide that Zheng must be summoned and the intruders must be apprehended. Zheng communicates to the Committee that Mondas is entering the region of unstable space sooner than expected and asks that emergency strategies be implemented immediately. The Committee summons Doctorman Allan who does not answer. They determine she is no longer reliable. The Committee decides to delay emergency strategy and bring Zheng down from the surface to restore order.

In Dodd's shop, Mr Hartley is talking to Dodd about some credit, since he used up all his rations when Nyssa was at the house. While this is happening, the Doctor walks in. Dodd refuses credit for Mr Hartley. Hartley asks if the Doctor is a friend of Nyssa. The two introduce themselves. Dodd pushes Hartley out of the shop to speak to the Doctor. Dodd finally asks the Doctor what he wants...

The swarm of Cybermats are pushing their way into the TARDIS. Frank is worried about being overrun, but Nyssa tells him that the ship can stand up to far worse. Nyssa then questions if Frank shut the outer door. Frank looks over as the door begins to buckle.

The Doctor tells Dodd that he wants to get to the Committee Palace. He needs to see how far along the processing has gone. The Doctor scolds Dodd for the way he packages his stock. Dodd complains that people want titanium and plastic, not what he's got to offer. Dodd complains that the process makes people go mad, so they have their emotions removed as well. He opens the door to the cold storage room and, as the Doctor steps inside, Dodd closes the door locking him in.

Nyssa decides that the way to stop the Cybermats is to reroute the energy to the TARDIS' outer shell, which fries the mats. She decides to pick up some food and head over to the Hartley home.

Yvonne stands in line, sobbing, wanting to leave and go back to her home. A Cyberman walks to her and takes to the processing area. We hear the machinery working as her processing begins.

The Doctor stares at the temperature gauge on the cold storage door, seeing it drop. The Cybermat got trapped in the room with the Doctor and he decides to test its defences before its owner comes to collect it.

The Cybermen break down Dodd's door looking for the Doctor. Dodd tells them that he's escaped through the back door. The Cybermen open the cold storage door and find the Doctor inside. The Cyberman leader tells the others to destroy him. The Doctor brings down some of the storage boxes on top of them, giving him a chance to escape.

The Doctor finds the policeman's cyber-converted horse. The horse bucks against the Doctor. Allan shows up at the same time as the Cyberman and overrides his commands concerning the Doctor taking him to her laboratory. Dodd is also taken away by Doctorman Allan.

Frank shows up at the house with Nyssa, who brought provisions. Mr Hartley says he met the Doctor at Dodd's place. Frank is furious wanting to know what he's doing there, but Mr Hartley avoids the question. The television broadcasts, again in '50s newsreel style, the new uniforms that the cyber-workers will be wearing on the surface. Frank exclaims that they're nowhere near the surface. Nyssa tells them that they're not uniforms, they're fully processed Cybermen.

The power suddenly goes out in the city. Sisterman Constant is ordering staff to get the backup generators working, as the recruits' programming hasn't been completed yet. The evacuation bell rings. The staff tries to restrain the partially processed recruits who are asking what their task is. Constant asks where Doctorman Allan is. Constant hears a noise coming through the communication system and realises that it's the Committee.

A loud rumble echoes through the city. The Doctor tells Dodd that the air pressure has dropped. Dodd replies that it sounds like the roof is caving in. The police continue to push the citizens of the city through the Committee gates. Dodd doesn't want to go inside. The Doctor thinks that he might have been wrong, that Mondas may not have a future after all.

Popping the Seals (3)
As the Doctor and Dodd are being pushed through the gates, a piece of the roof falls in and crushes the policeman. The Doctor and Dodd run into the Committee palace to escape the rubble.

A partially processed Cyberman asks Sisterman Constant about their tasks. She tells them that they are to stay where they are until the power is restored. Doctorman Allan shows up asking why the recruits are here. Constant explains about the loss of power and how the staff is trying to contain them, but at least one walked away. Constant says the recruits don't understand, but the cyber-recruit answers that he does understand, saying he is the future and asks again about his tasks. Allan tells him that they all have to wait. She asks about the Committee, saying without power they will die. The hospital has been cut off and no one can leave. Allan decides the Committee is in trouble. The cyber-recruit tells Allan that their first imperative is to protect the Committee and asks where they are. Allan tells them to continue waiting. The cyber-recruit advises that if anyone threatens the Committee, they will be destroyed.

The Doctor and Dodd get away from the policeman and are hiding in the palace. The Doctor notices that it's beginning to get colder, that the outside is getting in. Dodd asks if they're safer in there, to which the Doctor explains that it depends on what's in here. They find a number of statues, which are gold leaf. The Doctor scrapes some of it off, thinking it could come in handy later on. He asks Dodd what happened to the former leaders and Dodd tells him that they were executed. The Doctor wants to know where the Committee is; he wants to see them for himself. Dodd says that no one sees the Committee.

A cyber-recruit wanders into the palace, asking what their task is. The recruit sees the Doctor steps out. Dodd says how horrible it is, that it's not even human anymore. The Doctor wonders why it doesn't know its task and asks who it used to be. The cyber recruit remembers, "Father must see my uniform" and repeats the Hartleys' address. The Doctor tells Dodd that the recruit is still wired and fresh from processing. He says it's Dodd's future: a Cyberman.

Nyssa says that it is snowing outside. Mr Hartley says they don't get weather anymore and this would be a blizzard. Frank tells Nyssa that the work crews were drilling to the surface. Mr Hartley thinks it's beautiful. Nyssa says she has to find the Doctor.

Doctorman Allan tells the cyber recruit that she has to reach the Committee chamber. The recruit says they have to protect the Committee. Allan convinces him that she needs to get the generators restarted. After considering, the recruit says she can go but one of them will accompany her.

Dodd and the Doctor are still roaming the palace when the Doctor finds body containment suits. He deduces that they're going to start processing on an industrial scale. Dodd has seen enough and leaves.

Doctorman Allan comes down the hall with the cyber recruit. She tells him to keep watch, but he insists that he must escort her. The Doctor comes out from his hiding and throws the gold leaf from the statue at him. Unexpectedly, it has no effect. The Cyberman attacks the Doctor. Doctorman Allan disables the Cyberman with a failsafe override, which only works during processing. The Doctor questions if the processing was complete. The Doctor offers to help get the generators back online. Doctorman Allan doesn't trust him but doesn't have much choice and they head to the generators.

Nyssa and Frank arrive at the TARDIS and begin banging on the door. There's no answer from the Doctor. She decides that they should try the Committee palace; they can try to find Yvonne there too. As they're about to leave, they see lights coming at them. The police are in the area. They leave and go in another direction towards the palace.

The Doctor and Allan arrive at the generator chamber. The Doctor notices that they are using Geothermal power. Allan looks at the printouts and notices that every failsafe has been activated. The Doctor surmises that someone has been making enormous demands on the power. He tells Allan that time is running out and the planet is heading towards the Cherrybowl Nebula. The Doctor questions Allan quickly about the Committee: how it is a single entity and opens a door to find an empty room. The Doctor tells her that there is no Committee anymore. Suddenly, electronic noises fill the area. Allan exclaims that they're still alive.

The cyber-recruit tells Sisterman Constant they can't wait any longer. She tries to leave but the cyber-recruit tells her to stay where she is. They tell her that she should become like them; her ability to feel cold is a weakness. She says they were built for a purpose. The cyber-recruits repeat that. They say she knows their purpose and must tell them. The cyber-recruit grabs her arm, holding her tightly. The door opens and Zheng and his squad enter the ward, assuming control. He tells the recruit of release Constant. The recruit refuses and Zheng shoots him. Zheng tells them to return to their task. Constant tells him that the processing cut out because of the power. Zheng has his squad take the recruits back to the processing section. He wants to know why the power hasn't been restored and if the Committee is safe. Constant tells Zheng that Doctorman Allan is down there now. Zheng notices that Constant's arm is broken and orders his squad to take the fallen recruit and Sisterman Constant to the reassembly area. Zheng tells her that resistance will not be tolerated.

The Doctor scolds Doctorman Allan about the Committee, calling it a "cybernetic multi-headed hydra" and now knowing why the generators are putting out so much power. Doctorman Allan explains that twenty of the greatest minds joined together in order to propose solutions to their problems. The Doctor describes the Committee saying they're swollen heads wired into the system with bodies withering like rotten fruit. Zheng enters the generator room asking why the power is not back on and who the Doctor is. He introduces himself as Allan's assistant and he's the only one who can restore the generators. The Committee comes alive and tells her that the main objective is to restore the power. Zheng reports to the Committee that radiation levels on the surface have increased and work on the propulsion systems was stopped because of the power loss. The Doctor realises now why Allan created the Cybermen; they built a propulsion system for the planet but only Cybermen would be able to install it due to radiation levels. Allan explains that now these conditions are extending into the city. She says without power, Mondas will be a dead world.

Frank and Nyssa knock loudly on the Hartleys' apartment door. Nyssa notices a swarm of Cybermats following them. As Mr Hartley opens the door, Nyssa notices the swarm leaving. A Cyberman comes up the walk and smashes through the front door.

The Doctor determines that the machinery is burnt out and he'll have to close the links manually. Grabbing a metal rod, he closes each circuit individually, saying the only real solution is to lead Mondas away from the nebula. Zheng tells the Doctor that the propulsion system is completely operational. The Doctor determines that only fully cybernetic workers are able to withstand the pressures; Doctorman Allan tells him the survival rate on the surface is only 19%. The Doctor continues closing the circuits.

The Cyberman breaks through the door of the apartment. Seeing Mr Hartley, the Cyberman becomes distressed. They realise that the Cyberman is Yvonne. Mr Hartley tries to remove the mask and Yvonne becomes crazed and begins to wreck the apartment.

The Doctor is down to two circuits left and asks what happens afterwards. Zheng states the Committee will restore order, but the Doctor and Doctorman Allan tell him that power must first go back to the city. The Doctor threatens to smash every circuit if they don't agree. The Committee agrees to their demands. The Doctor tries to throw the final circuit but it's jammed. He forces it out as Zheng throws the switch restoring power. The Doctor screams as the power is restored, taking the full force of the power levels. Doctorman Allan says he's dead.

Yvonne moves wildly around the apartment, smashing whatever is in her path. Nyssa and the others try to hold her. The power goes back on and Yvonne's bird begins to sing and the lights on the tree come on. Yvonne is fascinated by the lights and sounds. Mr Hartley takes her over to the tree, trying to help her to remember what each item stands for. Yvonne begins to cry.

Sisterman Constant is strapped to the processing conveyor as the power comes back on. She pleads with the Cyberman to take her off the belt. Her voice fades as she goes through the conversion process.

The Committee is back online and quickly decides that the propulsion system must be tested and an evaluation of the city must be completed. The Doctor wakes up looking for Nyssa. Doctorman Allan tells him to rest. She tells Zheng that the Doctor took the entire power supply and is hardly burnt. She wants to do a complete physical assessment of the Doctor thinking that using his physiology, she can create more effective Cybermen.

Yvonne stops moving and falls to the floor. Nyssa determines that she's receiving radio signals now that the power has been restored. Yvonne calls for her father and Frank as she dies.

Doctorman Allan places the Doctor on the scanner table. He continues to ask about Nyssa and if she's all right. Zheng tells Allan that Constant has been sent for processing. Zheng tells Allan to look at the Doctor's scans.

Frank sits on the steps outside the apartment looking to the North. Nyssa goes out to him and sees that the frozen atmosphere has broken through the roof and a mist is enveloping the city. Frank says that it's gotten to the hydrahouse where they grow all the crops and if they don't freeze, they'll starve to death.

The Doctor is woken up by Dodd who was unable to get out of the palace gates. The Doctor is too weak from the testing to stand up. He asks Dodd to phone Mr Hartley and see if Nyssa is there. Dodd asks what he'll get in return, and he'll need a new stock for his shop.

Frank is still sitting outside in the cold. Nyssa tells him to come inside as his father is asking for him. Frank yells at her; asking who she's ever lost. The phone rings and Frank answers then hands the phone to Nyssa. The Doctor tells her that he's in the Committee palace and wants her to grab a few things from the TARDIS workshop. She quickly tells him that she can't get in, as it's locked and she doesn't have a key. The Doctor thanks her and says he'll try something else. Suddenly, another Cyberman breaks through the apartment door telling Nyssa that she will come with him.

The Doctor hears the commotion on the phone and realises something is wrong. Doctorman Allan walks in with Zheng. Zheng grabs Dodd and takes him down for processing. Allan shows the Committee the scans from The Doctor. They notice he has two hearts, but Allan tells them there is a small lobe at the base of his skull which deals with bodily and motor functions. She thinks she can use that to optimise data for the Cybermen. She thinks she can reproduce this in all new cyber processing and there will be no need for organ rejection. The Committee agrees and says this is to begin immediately. The Doctor refuses, saying he will be no part of this. Allan pleads with him. The Committee tells Allan to begin, that they will survive and will be invincible.

Shelter (4)
Mr Hartley sits with Yvonne's cyber converted body. Frank tries to get him to leave her and says that the police took Nyssa. Mr Hartley ignores him, still watching his daughter.

The Doctor struggles as Doctorman Allan begins her scans. The Doctor screams that he will not be a part of this, asking how Allan can do this to her people. She replies that this is the only way they can survive; only Cybermen can go on the surface of the planet and save Mondas. The Doctor hisses that he will not assist her in her tests.

The Committee questions Zheng as to why the propulsion systems have not been testing. He states the power is not full yet. Power is also needed for the shields over the city. The Committee talks among themselves, then tell Zheng that all citizens of the city must go for cyber-conversion. They tell him to begin with police and nursing staff.

There are more explosions and Mr Hartley tells Frank that the ice flow has gotten as far as the church. An announcement is broadcast that there is a state of emergency and all citizens will be sheltered in the Committee Palace.

Allan notices that the turbulence is getting worse. The Doctor tells her to get the propulsion system working. Nyssa sees the Doctor and runs in to see him. Zheng ordered her to be brought in for questioning. The Doctor says that Nyssa can help Allan. Allan tells the police that Nyssa is to stay with her. Nyssa tells the Doctor and Allan what's going on outside. Nyssa tells Allan that cyber processing killed Yvonne. She is shocked as full processing was only to be for selected workers. Zheng tells Allan that all citizens are to be processed and his staff is not programmed to do the operations. Zheng then notices Nyssa and asks why she wasn't brought to him for interrogation. Allan says that she can help with the new template. Zheng relieves Allen of her duties and begins the Doctor's scan himself. Allan screams that the Cybermen are her works. Zheng says she should be proud, while she still has the capacity. The Doctor screams as the scan starts; the Committee tries to get into the Doctor's head. They argue about Mondas' future and the survival of their people. Zheng continues his work. The Committee tells the Doctor that he will soon be just like them. He screams and passes out.

The Committee discusses the Doctor and decide that he will be processed. They decide that they are the future, and the cyber race is secure.

Nyssa asks how much longer the scan will take. Doctorman Allan is pouring herself another glass of wine. Zheng tells her that it is nearly completed. Another Cyberman comes in to tell Zheng that the citizens are at the gate. He decides to go to the gates and leaves Doctorman Allan in charge.

Frank and Mr Hartley stand at the gates with the rest of the population. Franks asks how much longer and says it's getting colder. Mr Hartley refuses to go inside. There is a crackling noise and Frank asks what that is and Mr Hartley tells him to get back.

Zheng says that if the crowd does not go through the open gates, he will use their emotional responses against them and drive them in. He orders the troops to be ready for the intake of the population.

The scanner finishes its processing and Nyssa quickly opens the door to find the Doctor gone. Allan laughs and continues drinking. Nyssa screams at her that she tricked her and the Doctor has been processed. The outer door slides open and a Cyberman enters. Allan marvels at the smooth movement of the new design. Nyssa calls to the Cyberman, thinking it's the Doctor. Allan laughs as the Cyberman is summoned with new orders and leaves.

Cybermen come from behind the crowds to force them inside the palace gates, using whips. Mr Hartley tries to resist but is hit with the whip and moves inside.

The Committee asks for Zheng's report. He says the crowds are resisting and the Committee tells him that more power must go to the processing centre and resistance must be crushed. Zheng tells the Committee the propulsion unit is ready for testing and power must be diverted. The Committee says that the security of the Cyber-Planner overrides all commands.

Nyssa asks Allan if there is a way to stop the Committee. She doesn't care and continues drinking. Nyssa explains that the Doctor and Adric and countless others have been killed by her Cybermen and she has to find the Committee. Allan says she knew she was right and should thank the Doctor for what he's done to help.

The outer door slides open and the Doctor walks in. Nyssa says she thought that the Cyberman who walked in was the Doctor. Allan explains that was the first recruit from the Doctor's new template; he used to be Thomas Dodd and the template is on its way to the processing line. The Doctor laments that every Cyberman he'll ever meet is now based on him. They decide that there must be some way of stopping the Committee. They decide that since medical supplies are not available, they will pour Allan's wine into the nutrient that feeds the Committee.

The Cybermen are continuing to force the citizens into the Committee palace. Frank and Mr Hartley try to move away from the crowds as the ice outside causes the roof of the city to cave in.

The Doctor and Nyssa begin to pour the wine into the nutrient that feeds the Committee. Allan grabs at the bottle. She and Nyssa struggle and Nyssa pushes her down. Allan storms out of the room heading to see the Committee. The Doctor now decides that he can destroy the Cybermen since they've been created in his image. Nyssa wonders that if the Cybermen are the only way the people of Mondas can survive, do they have the right to change that? The Doctor replies; "the people think this is the end, but we know its only the beginning." They keep pouring the wine into the vat.

A Cyberman from the surface contacts Zheng to tell him that radiation is increasing and power must be restored to the propulsion system. Zheng heads to the Committee to receive the order, meeting Doctorman Allan in the hall. She tries to tell Zheng that the Doctor is trying to poison the Committee. Zheng asks what is more important, the Committee or Mondas. She tries to stop Zheng to warn the Committee herself. Frank and Mr Hartley are hiding in the halls near where the conversation is happening. They hear Allan mention the Doctor and run off to try to find him and Nyssa.

The Doctor and Nyssa finish pouring in the wine. They look out to the city and see that half the city is buried under the glacier. They decide they must change Mondas' course, it won't be able to survive against the endless cold. A Cyberman walks up to them, saying that all civilians must be taken for processing. The Doctor tries to reason with the Cyberman, but it grabs him and Nyssa. Frank comes up from behind and hits the Cyberman, forcing it to let go. The Doctor and Frank, along with Mr Hartley, grabs the Cyberman and throw it out a window to the ground below. The Doctor and Mr Hartley head towards the Committee. Frank stops Nyssa, apologising for how he acted before. They look down and see a squadron of Cyberman. Frank tells her they're processing everyone. They run off to warn the Doctor. A Cyberman grabs Nyssa and Frank saying they are to be processed.

The Doctor and Mr Hartley reach the generator. They discuss quickly how to divert the power when they hear Doctorman Allan yelling, trying to persuade the Committee about the wine in the feed lines. They state that nothing has been detected. They also decide Doctorman Allan is no longer needed. Zheng reports that the surface crews need power to the propulsion system and that they must get away from the Nebula. Allan keeps screaming about how the Committee has decided to process everyone. Zheng again states that the propulsion system must be activated. Allan says the roof must also be repaired. The Committee ignores Zheng and has Allan taken away for processing.

Mr Hartley tells the Doctor that if they can alter the energy pulse, it can act as a huge mat trap. The Doctor distracts a Cyberman so that Mr Hartley can work on the generator.

Doctorman Allan is taken to the processing centre, where she meets Nyssa and Frank who are also waiting in line to be processed. Frank screams at Allan about what happened to Yvonne. A Cyberman pushes him back in line.

Mr Hartley continues to work on the generator, pushing it to the highest setting. The Doctor reaches the Committee. He tries to convince them to stop the processing. The Committee stutters in their response and the Doctor realises his plan is working. He tells Zheng to use the propulsion system now or all the people and the whole planet will die. Zheng agrees with the Doctor, he attempts to activate the propulsion system but is attacked by the Committee. The Doctor continues arguing with the Committee.

Nyssa, Frank and Doctorman Allan are placed on the conveyor belt. Suddenly, a swarm of Cybermats run past them. The Cyberman stops the processing and says to alert the Cyberplanner.

The Committee explains that Mondas was pushed out of its orbit by a moon forming between it and its twin planet, destroying the equilibrium. Their research showed that Earth thrived while Mondas dies. The Committee is having difficulty focusing as the wine is getting into their system. The Cybermats begin eating away at the generators. The Doctor tells Zheng that he must divert the power now or it will be too late. He tells the surface crews to activate the propulsion system. Mondas begins to move away from the nebula.

The Doctor is sitting outside. Nyssa shows the Doctor calculations showing that Mondas is moving back towards Earth and away from the Nebula. The Doctor states that the Cybermen would have happened anyway, the nebula was just an excuse. The Doctor thinks the Cybermen can turn out for good if they and the humans can live together. The Cybermen are already working on the roof and the city is warming up.

Thomas Dodd, now a Cyberman, walks up to the Doctor telling him that he has been requested to supervise the reconstruction of the city. The Doctor refuses, saying he has to go. Mr Hartley tells the Doctor that Doctorman Allan will use his notes to try to reverse some of the processing and make the Cybermen a bit more "human". The Doctor notes that at least Allan shut down the processing centres. The TARDIS quickly takes off.

Doctorman Allan is talking to Sisterman Constant, who is now a Cyberman. She says that Constant hasn't looked at the Doctor's notes. Constant tells Allan that the logical course would be to increase processing. She tells Constant that they have a new future, thanks to the Doctor. The door slides open and Zheng walks in.

He says "Doctorman Allan, we begin again."

Cast

 * The Doctor - Peter Davison
 * Nyssa - Sarah Sutton
 * Doctorman Allan - Sally Knyvette
 * Sisterman Constant - Pamela Binns
 * Thomas Dodd - Derren Nesbitt
 * Dad - Paul Copley
 * Yvonne Hartley - Kathryn Guck
 * Frank Hartley - Jim Hartley
 * Mrs Ginsberg - Ann Jenkins
 * Cybermen / Cyber-Commander Zheng / Radio Announcer / Nurse / Citizen - Nicholas Briggs
 * Minister / TV Commentator - Alistair Lock
 * Philpott / Nurse - Gary Russell

Species

 * Yvonne has a pet Cybermat.
 * The Doctor tries to fight off a Cyberman with gold dust, but it has no effect.
 * Part of the Cybermen design is structured after the Doctor's own brain.
 * A Cybermat given to Nyssa as a gift damaged the TARDIS console but was destroyed by the Heart of the TARDIS.

Foods and beverages

 * Doctorman Allan drinks wine.
 * Nyssa gives the Hartley family some tea leaves she found in the TARDIS. The Doctor explains sternly that they came from the Emperor of China and he was saving them for a special occasion.

Continuity

 * This story takes place at the beginning of the Cybermen's creation. Many of its events lead into those of TV: The Tenth Planet. The Twelfth Doctor would also witness the origins of the Cybermen on Mondas' Colony Ship (TV: World Enough and Time and The Doctor Falls).
 * Mondas began to drift through space, due to the sudden arrival of a moon between Earth and Mondas. This upset the gravitational equilibrium of Mondas, causing it to escape its orbit. (TV: The Tenth Planet)
 * Cyber-Commander Zheng would return for a cameo appearance in AUDIO: The Reaping. That story depicted him as still being operational in September 1984.
 * Nyssa recalls Adric's death. (TV: Earthshock)
 * Nyssa has sympathy for people losing their family. (TV: The Keeper of Traken, Logopolis)
 * The Cybermen, helped by Missy, would use the dead to a greater extent for cyber-conversion in TV: Dark Water / Death in Heaven.