Inferno (TV story)

Inferno was the fourth and final story of Season 7 of Doctor Who. It was the last story to feature Caroline John as Liz Shaw, although her departure is not depicted. It was also the first Doctor Who story to explore the concept of parallel universes.

Inferno was the first story in which producer Barry Letts had any say on development and commissioning. Director Douglas Camfield fell ill after completing parts one and two. This left Letts to direct the other five parts.

Several possible stories were considered for the season finale. The Mists of Madness by Brian Wright and The Shadow People by Charlotte and Dennis Plimmer were two. However, Wright was unavailable and the Plimmers abandoned the project after a pay dispute. This left the way open for The Mo-Hole Project, as it was then titled, by Don Houghton. The serial went through several name changes before becoming Inferno.

Houghton had based the drilling part of the story on real events. He had contacted the American Embassy to enquire about, a real world attempt to drill through the Earth's crust. Information on the project and why it was abandoned was not disclosed as such information was top secret. It was this secrecy that Houghton developed upon for his story.

Letts was worried when the first script draft arrived as he did not think there was enough in it to fill a seven-parter. Additions such as the Primords and scenes featuring Venusian aikido were made to suitably lengthen the script.

Synopsis
UNIT is providing security cover at an experimental drilling project designed to penetrate the Earth's crust and release a previously untapped source of energy. Soon however the drill head starts to leak an oily green liquid that transforms those who touch it into vicious primeval creatures with a craving for heat.

The Doctor is accidentally transported by the partially repaired TARDIS control console into a parallel universe where the drilling project is at a more advanced stage. Thwarted by his friends' ruthless alter egos, he works to save both universes.

Episode 1
The Doctor drives Bessie into an area marked restricted.



A maintenance worker by the name of Harry Slocum enters a drilling unit nicknamed Inferno. He introduces himself to Sir Keith and is told there is an issue with pipe number two. He is urged to fix it quickly as Professor Stahlman does not want any delays. The Professor is at loggerheads with Sir Keith and tells him he should never have stopped the pipe for maintenance. He tells Sir Keith never to make a decision with regards to the drilling again.

As Slocum is fixing the pipe he sees a green goo emanating from the base. He touches it and it burns. He is horrified to see his hand turn green.

Sir Keith discusses the Professor with his Personal Assistant Petra. He confides that he has sent for an expert in oil rig mining, Greg Sutton, as he is nervous that there is no one with real drilling expertise on the mission.

As Slocum leaves he seems entranced. He heads outside the complex and stumbles against a piece of scaffolding. A man rushes out to help him. With a growl Slocum turns on him and kills him with his wrench.

In a room inside the complex, Benton is hanging s picture in what is to be the UNIT HQ. The Brigadier enters and asks if there has been any sightings of Slocum. Benton says there hasn't been. The Doctor enters and the Brigadier tells him of the murder. He shows him the wrench. It is still warm and, when it was found, it was red hot. The Brigadier comments that trouble seems to follow the Doctor around and he questions why he asked to be on this mission. The Doctor says that an opportunity to be at the first penetration of the Earth's crust was not to be turned down. He heads off to do some experiments of his own.

Sutton has arrived and is bewildered at having been pulled over with such urgency. Sir Keith shows him around the complex. He says that the drill head is twenty miles deep. This has been achieved by having no pipes - the pipes visible containing coolant delivered to the drill bit. Instead there is a robot drill that is fed by a cable from a nuclear reactor. Sutton asks what this is hoping to achieve. The project is aiming to pipe Stahlman's Gas - named after the Professor - a powerful energy source trapped inside the Earth's crust since the dawn of time. Sir Keith begins to introduce Sutton to the staff. He tries to flirt with Petra and is snubbed. On introduction to the Professor he is cold. The Professor thinks that Sir Keith is trying to introduce as many experts into the project as he can to try and close it down. He counts the Doctor as one of these. Sir Keith introduces Sutton to the Doctor and asks his opinion on the project. He says that they should be heeding the warnings of the computers. As he leaves he overhears the Professor complaining about the experts to Petra. He causally, but loudly, points out a flaw in the mechanics to a near by scientist - causing the Professor's blood to boil.

The Doctor pulls up to a small building being guarded by a UNIT soldier. He asks if there is any news about Slocum- he is told that there isn't. The Doctor uses a device to open the door to the building remotely and drives Bessie in. Liz is inside working on the TARDIS console. The Doctor hands over the figures from the computer and tells her of the murder. She already knows as the sentry told her. They discuss the real reason they are here. The Doctor wants to use the nuclear power to try and jump start his TARDIS console. He wants a test run straight away. Liz starts flicking switches and positions herself by the main switch.

Slocum is skulking around the complex. He is now covered in hair and has claws. He enters a building. A member of UNIT is in the phone. Slocum approaches him from behind.

The Doctor says he is ready. Liz pulls the lever down. The machine registers 7 mega volts.

Slocum has killed the UNIT soldier. He pulls a switch down to maximum.



The console begins to shake. The Doctor says that there is too much power. Liz cannot do anything as the circuits are locked. The console and the Doctor dematerialise.

The Doctor is in some kind of limbo and is in some pain as he and the console fly through the darkness. He flies off into the black.

Liz uses a plank of wood to force the levers down.

The Doctor and the console reappear. The Doctor is groggy but fine. He is keen for another trial run. Liz tries to dissuade him but he says he needs to know where he was. An alarm goes off. It is the drill head. The Doctor and Liz hurry off to Bessie.

The complex is in lock down as the drilling room fills with smoke. The Professor argues with Sir Keith as to why he ordered the lockdown. Sir Keith implores him to shut off the power but he refuses. Sutton says that if the power is stopped now it will never be able to be restarted again. Petra is ordered to go and check the coolant. Sutton tries to stop her saying that the pressure is too dangerous but she doesn't care. The Doctor and Liz enter. The Doctor says that there has been a nuclear power surge. The Brigadier enters and says that there has been another murder. The Doctor goes to the Professor to give him his advice but he tells him to stop wasting his time. The Doctor heads off with the Brigadier. Petra returns saying that the controls are jammed with the heat. Suffolk tries to stop her from heading off but instead goes with her to help. They find the Professor trying to stop it manually. Sutton helps.

The Doctor and the Brigadier go to examine the body. As they do Slocum jumps up, growling.

Episode 2
The Doctor stops any UNIT forces from attacking.

Sutton has sorted the issue with the coolant. The Professor says the readings are too high. He gets offended when Petra suggests they need the Doctor.

The Doctor tried to calm Slocum. A UNIT solider, Private Wyatt, sneaks up on Slocum and prepares to attack.

The Professor is trying to contact the Doctor.

The phone is ringing but all ignore it. Slocum attacks Wyatt. Wyatt manages to shoot him twice. They wrestle and then Slocum slumps to the ground.

Sir Keith wants to stop the drilling but the Professor blocks it.

Slocum is wounded but alive. The Doctor wants to turn off the switch but can't as it is too hot. He borrows the Brigadier's gun and uses that. Slocum dies. As he slumps down the wall he was leaning on is blackened and scorched. He answers the phone and tells the Professor he has sorted everything.

The Professor tells his workers to return to their duties. Sutton is cross at him and says he is just asking for trouble. He tries to confide with Petra and implores her to try and persuade the Professor.

The Doctor and the Brigadier examine the body. He was shot twice through the heart but remained alive for several minutes. The Doctor marvels at his abnormal resistance and strength. The body is still hot. The attacked UNIT scientist and Private Wyatt are seemingly fine.

The Doctor and the Brigadier climb to the roof to discuss what is going on. The Doctor suggests that there is some kind of retrogression of body cells that cause the victim to turn into animals. The Doctor says that it is a very slow process and wasn't complete with Slocum. The Brigadier asks if he has ever heard a noise like the one Slocum made. The Doctor says he has; at Krakatoa in 1883. The Brigadier asks if there is a link. They are interrupted by a UNIT soldier who reports that Wyatt has disappeared. The Brigadier and the soldier rush off to find him. The Doctor sees him high above on a walkway and pursues him. When he catches up Wyatt is animalistic. He approaches the Doctor, wielding his gun like a club. He swings too hard and throws himself off the edge of the walkway. The Doctor shouts for no one to touch him.

The UNIT scientist emerges from the building in a trance.



The Professor wants to increase the drilling speed. Petra calls him into a room where Sir Keith and Sutton are examining something. They open a box and show the Professor a vile of the green goo. Sir Keith says that it has defied analysis and that it is very tricky to analyse as it is too hot and does not cool down. The Doctor tries to suggest what it is - again mentioning Krakatoa. The Brigadier wants to talk to the Professor and Sir Keith. The Professor is reluctant to comply. The Brigadier insists. Left alone Liz and the Doctor discuss the substance. The Doctor says he wants to hear it as he thinks it will let off a scream. Liz asks him to come and look at one of the computers.

The Professor is callous and is not bothered about the deaths on his site. The Brigadier and Sir Keith plead with him to show more mercy. He says he has no time for these deaths nor any crazy theories of the Doctor's. The Doctor enters and asks if the Professor ever intends on paying heed to his computers. The Professor insists that the computers are over sensitive. The Doctor reacts angrily. Petra rushes in and says that the vial holding the green goo is about to break. The Professor strides out and, against the Doctor's suggestions, takes the vial in his hands and outs it back into the box. He orders it to be deep frozen. The Professor makes it clear that his discussion with the Brigadier is over and that the computer is faulty. The Doctor shows the Professor the computer and warns him that he should stop the drilling. Again, the Professor says that the readings are inaccurate. The Doctor goes to leave. The Professor tells him that he is taking away his nuclear power that he has been using to experiment with the TARDIS. The Doctor tells him that he is being childish. The Professor tells Petra that they can up the work rate of the drill in 25 minutes. Petra asks if it is safe but the Professor disregards her. As he is left alone, he discovers that his hand is green.

The Doctor asks Liz to go back to their hut and test the Tri-Gamma Circuits on the console. Subtly he flicks a switch on one of the computers and poses his hut back up.

The Professor enters and opens the computer and removes a microcircuit. He finds a truncheon in the Brigadier's desk and goes to smash it. The Doctor stops him. He goes to do it again and the Doctor uses Venusian Karate to paralyse him. The Brigadier breaks it up. The Professor leaves saying that the Doctor is a mad man. The Doctor tells the Brigadier what he saw. When they challenge him the Professor accuses the Doctor of trying to sabotage the drilling. They check his pockets and he no longer has the microcircuit. As the Doctor leaves he points out that the computer is already stopping working. Unseen, the Professor stamps on the microcircuit which he had dropped on the floor.

The Doctor returns to his hut. Liz has fixed the Tri-Gamma Circuits. She asks why he asked her to do it and he says he strongly believes that the console is fine it is just the nuclear surge that ruined his test. Liz says she is relived they can't test again. The Doctor sends Liz off to run some tests through the computer. As soon as he is alone he busies himself with the console.

As Liz leaves she is pursued by the animalistic form of the UNIT scientist.

Liz returns to find the computer broken. When she explains to the Brigadier why she is there, he says that the Doctor knew the computer wasn't functioning. Liz rushes over and sees that the switch to provide power to the Doctor's hut is on. She and the Brigadier run off.

The Doctor hangs onto his console as it begins to shake.

The Professor notices that the power is down. He runs over to the switch and switches the Doctor's power off.

Liz and the Brigadier return to see the Doctor and his console dematerialise.

Episode 3
Liz tries to bring back the now disappeared Doctor but there is no power. He is trapped.

Liz and the Brigadier return to the base. The Brigadier orders the Professor to reconnect the power and explains why. He refuses. Sir Keith threatens to tell the Ministry about this and the new mining speeds. The Professor tells him to do so. When the Professor leaves Sir Keith says he will go to London as soon as possible but can't leave the Professor to do as he pleases at this critical point of the drilling.

The Professor's hand is now bright green. As he puts some gloves on he is seen by Petra who tells him to get it checked. He tells her not to worry.

Liz berates the Brigadier for not showing concern over the Doctor. The Brigadier says he has many concerns of which the Doctor is one.

The Doctor awakes. His surroundings are somewhat altered. On the wall is a poster that reads 'Unity is Strength.' His device does not open the door so he forces it open. The shed door has a sign reading 'Technical Store' with an unfamiliar logo on it. He drives Bessie out of the garage and pauses to close the door when he is shot at by soldiers. After protesting he jumps aboard Bessie and drives off, pursued by the soldiers who consider him a saboteur. He soon finds himself in a dead end where a soldier jumps aboard Bessie. The Doctor and the soldier fight as the Doctor drives. He manages to throw the soldier out of the car. He parks Bessie between some houses and hides in a bin. The pursuing soldiers run into the house allowing the Doctor to escape. The Doctor sneaks onto a walkway above the compound and watches the soldiers look for him. He hears a snarl behind him and one of the animalised humans approaches him. As he attacks the Doctor uses a fire extinguisher to subdue him. This draws the attention of the soldiers who continue to pursue him. Another animalised human approaches him. The Doctor counters his attack with a wooden pole.

Below the soldiers are ordered to shoot on sight. They see a figure above them and shoot. The animalised human falls to the ground.

A female figure marches though the compound. The Doctor sees that it is Liz only with a different haircut. The Doctor draws attention to himself and asks why she is wearing those clothes. The woman looks confused, draws a gun and blows her whistle for backup. She orders they take him away.

The Doctor is brought into the Brigadier's office where he is met with a figure similar to the Brigadier but with an eyepatch and a large scar by his eye. He asks how the Doctor got in. The Doctor responds quizzically and asks who he is. The man reveals himself to be the Brigade Leader Lethbridge-Stewart while the woman is Section Leader Elizabeth Shaw. When he asks who the Doctor is, the Doctor realises what has happened. He introduces himself as a Doctor John Smith and says he is from a parallel space time continuum. The Brigade Leader is unsure if he is mad or bluffing. The Doctor shows he has knowledge of the drill and the people running it. He wants to see Professor Stahlman or Sir Keith. The Brigade Leader takes him to Director Stahlman. On the way the Doctor notices that the drilling is three hours and twenty minutes away from the core - much in advance of where the Doctor has come from. When the Doctor is brought to the Director he asks to see Sir Keith. The Director tells him that Sir Keith was killed in a car accident on the way to the ministry in London. The Doctor draws attention to the broken computer that was giving out warning signs before it broke down. The Director accuses the Doctor of having broken it and calls him away. He turns to Doctor Petra Williams, the Assistant Director of the project and asks her to continue to continue the drilling. Sutton tells her that there is no pressure getting to the drill head. Doctor Williams tells him that she is aware of this. Doctor Williams tells the Director what Sutton told her. He refuses to decelerate. Once he is left alone he feels a pain in his hand. He takes off the glove and it is bright green all over and hairy.

The Doctor is being made to wait by the Brigade Leader. He asks what is going to happen to him and is told that he will be executed without trial under the Defence of the Republic Act 1943. When the Doctor asks about the Royal Family he is told that they were executed. When the Doctor tries to sit down he is forced to his feet by the soldiers. When he badmouths them, the Brigade Leader tells him he cannot insult the Republican Security Forces who have been brought here to protect the drilling. The Doctor says they will need protecting if the computer that was giving out danger signals or the death of Harry Slocum is anything to go by. The Brigade Leader says he is showing the amount of knowledge that only a spy could possess. The Doctor insists that he has seen it all in his world. The phone rings and the Brigade Leader rushes out. Elizabeth tells him that Central Records have returned no match for the Doctor. This confuses the Brigade Leader as Central Records have never failed him before. They both go and interrogate him.

Doctor Williams is informed of a minor leak in the drill head. Sutton questions her and is frustrated when neither she nor the Director seem to be bothered. An alarm goes off.

Hearing the alarm, the Brigade Leader and Elizabeth rush out. The Doctor calls over the guard and immobilises him with Venutian Karate.

Smoke and green goo are pouring out of the drill head. The Brigade Leader is ordering all of his men and all of the scientists to remain at their posts. In amongst this chaos, the Doctor sneaks forward.

Sutton orders the scientists around to no avail. Doctor Williams watches the reading increase. The scientists start to abandon their posts - the Brigade Leader threatens to shoot them. The Doctor has found a toolbox and is scrabbling around looking for a microcircuit. He is discovered by a member of the Republican Security Force who holds a gun to his head. The Doctor implores with him saying that he knows how to stop all this. The guard is unmoved and asks him if he is going to come with him quietly.

Episode 4
Elizabeth stops the soldier. The Doctor thanks her but she says that she only did so because it goes against procedure. The Doctor tries to buy time to fix the computer and eventually Elizabeth allows it. The computer begins to work and assesses the problems. The Director is angry that the Doctor has been allowed access to the computer. Sutton and Elizabeth stick up for him. Sutton and the Dictator argue about the safety precautions. Doctor Williams starts to listen to the Doctor's theories. The Doctor says that the heat and the pressure is proving too much for the velocity of the drill and that the only way to counteract it is to produce a reverse vortex by reversing all the systems. Reluctantly the Director agrees then sends the Doctor away. Elizabeth compliments the Doctor and then asks where he came from. He repeated his story about the parallel universe. She asks about the version of herself in the Doctor's universe. He says that she is a scientist. Elizabeth says that there is no similarity. The Doctor asks if she every contemplated being a scientist and she admits he studied physics at university. The Doctor points out that it is there where the two points diverged. Elizabeth is doubtful but the Doctor encourages her to think for herself.

Doctor Williams and Sutton talk about the Doctor and his motivations for saving them. Sutton says he intends on cutting the drill down to minimum speed irregardless of what the Director thinks. Doctor Williams tells Sutton that he needs to start towing the line a little more. Sutton refuses despite knowing that those that disobey orders 'disappear.'

Elizabeth is told that the emergency is over thanks to the Doctor. The Doctor warns Elizabeth about the dangers of the drilling operation.

The Director asks Sutton for progress and is told all is well. The Director tells Sutton he intends on increasing the drilling speed. Sutton says that this is madness. The Director threatens to dispose of Sutton if he continues to disobey him.

The Brigade Leader and Elizabeth are firing questions at the Doctor. They ask him: his name, who sent him, whether he is a saboteur, what organisation he works for, whether he is a traitor, how he gained access to the complex, who helped him and which of their enemies he is working with. The Doctor does not answer. Elizabeth warns him they have other methods of extracting this information and repeats the question. The Doctor says that he came on his own, by accident and has slipped sideways through time. Elizabeth asks the Brigade Leader for permission to go to Stage Two Interrogation. He blocks this as he is fearful the Doctor will die before talking. The Doctor hears the acceleration of the drilling and rises to try and stop it. The interrogation continues. The Director enters wanting to know what progress is being made. The Doctor draws attention to the Director's gloves and challenges him to take them off. The Director tries to brush over this but the Brigade Leader asks him to. He does so and his hands are bandaged underneath. He says that he scorched them. The Doctor begins babbling about the green goo and infection. The Brigade Leader orders the Doctor to be taken to the Security Centre and asks Elizabeth to supervise him into his cell. When they are alone, the Brigade Leader questions why the Director is so concerned about the Doctor. The pair squabble and the Director leaves saying he wants the Doctor "liquidated" by the end of the day.

Sutton and Doctor Williams conspire about the Director. Sutton is questioning why he is continuing to up the speed of drilling. Doctor Williams appears to be being convinced by Sutton.

The Doctor is escorted to his cell by Platoon Under Leader Benton. He notices he has a sleeping figure in the cell next to him. Platoon Under Leader Benton says he will be sleeping for some time as he has been shot with a tranquilliser dart. Elizabeth comes to check on him. The Doctor refuses to be interrogated any more, until Platoon Under Leader Benton orders him to his feet at gun point. Again, Elizabeth asks who the Doctor is and how he came to the complex. The Doctor, again, tells the truth. Platoon Under Leader Benton asks for a moment alone with the Doctor to extract the information from him. Elizabeth sends all the guards away. She puts to him that he is a protestor from a free speech group who is forming a demonstration and that if he confesses to that he will only get a few years in a labour camp. The Doctor refuses. Elizabeth says she will leave him to the Brigade Leader and leaves. Left alone, the Doctor tries to talk to the sleeping figure. After no response he goes to sleep. A green hairy hand emerges from beneath the sheets.

Back in the Doctor's universe, the Brigadier tells Liz that the UNIT soldiers have searched the entire complex for the Doctor to no avail. They will no extend their search beyond the complex. Liz is concerned that the Doctor could be anywhere in space or time. When the Brigadier says that the Doctor can look after himself, Liz warns that he is not indestructible.

Sir Keith asks the Professor is there are any problems or precautions with the drilling. He responds in the negative to both. Sir Keith says he is going to London and, unless he receives some kind of assurances, he will tell the minister of the unsafe practices being carried about by the Professor. The Professor says he has no intention of playing it safe. When the Professor leaves, Sir Keith tells the Brigadier and Liz that he is not sure that the Minister will even listen as he has been blinded by the Professor's promises of free energy. Sir Keith has an ominous feeling about the whole thing.

In the parallel universe, the Doctor awakens to snarling from the sleeping figure. He calls for the guard who enters to investigate. He is attacked and killed by the animalised human under the sheet. The creature approaches the Doctor and bends the bars to enter the Doctor's cell. The Doctor flips his mattress onto the creature, knocking him over. The Doctor escapes, locking the door behind him. He runs into the complex and approaches a truck. He is surrounded by people and in an effort to hide gets into the back of the truck as it drives off.

The drill is thirty five minutes from the centre of the Earth. Sutton asks Doctor Williams if everything is ready. Sutton has an ominous feeling about the whole thing and thinks they should be paying more attention to the computer.

The Doctor has found a full radioactive security suit in the back of the truck.

A guard discovers the carnage in the cell.

The truck draws up and the Doctor exits dressed in the security suit.

The drill is three minutes from the centre of the Earth. The Director stares intently at the readings.

The Doctor renters the compound with other similarly dressed men.

The drill is two minutes from the centre of the Earth. The disaster crew is at action stations. The Doctor and the other similarly dressed men enter the main area and line up. The Doctor sneaks away and begins to tamper with a computer. The drill is one minute from the centre of the Earth. The Brigade Leader notices the Doctor and calls to him. The Doctor unveils himself and shouts that the countdown should be stopped. The Director orders the Doctor to be shot. The Brigade Leader draws his gun. Sutton protests. The Doctor warns that they are about to release forces that they've never dreamed of. The drill lets out a high pitched shine. The Doctor warns that it is the planet screaming out in rage. Sutton attacks the Brigade Leader and implores the Doctor to run. Wherever the Doctor turns he is blocked by Resistance Security Forces. The Director now has the Brigade Leader's gun and is pointing it at the Doctor. The countdown reaches zero.

Episode 5
As Stahlman holds a gun on the Doctor, penetration is achieved, an explosion is heard, and an earth tremor rocks the installation. The temperature rises rapidly as more green slime oozes out of the cracked pipes. As the Doctor and the parallel Sutton try to contain the explosion, Stahlman attacks them. They manage to escape, leaving Stahlman behind a heat shield with the bodies of the unconscious workers. Stahlman rubs the slime on their faces, mutating them as well. There are seismic disturbances all over the country, and the Doctor explains that now that the crust has been penetrated, the planet will soon revert back to the gases it sprung from, saying they have "reached the point of no return", and that they will never be able to plug the hole, as nothing can withstand the immense pressures of the mantle.

When one of the Primords attack, the surviving people at the base find that they can be killed by cold from fire extinguishers. The government abandons them to their fate. The Doctor tries to convince the others that he can stop this from happening in his own universe if they will help him to return, and shows them the TARDIS console. He drains all energy from the TARDIS storage unit, and the Brigade Leader asks him to bring them back if they give him the necessary power. Meanwhile, Stahlman has fully converted into a Primord, and, in the original universe, Sir Keith's car has crashed.

The Brigade Leader demands that the Doctor save them, too, but the Doctor says that they do not belong in the other universe. Refusing to accept this, the Brigade Leader orders everyone back to the control room, where Stahlman and his fellow mutants attack, infecting Benton as well. In the office, the Doctor starts to explain his plan, but a Primoid's arm breaks through the glass...

Episode 6
Finally agreeing to help the Doctor, the group fights their way out using fire extinguishers to paralyse the mutants. By this time, the sky has turned red and the heat is overwhelming. The parallel Petra Williams, with Greg Sutton's help, manages to feed power to the TARDIS console. At the last moment, the Brigade Leader snaps and threatens to shoot the Doctor if he doesn't save them, but is gunned down by Section Leader Shaw. A wall of lava sweeps towards the hut and the others watch the end coming towards them.

Episode 7
The Doctor is back but unconscious in a healing coma, and there are only three hours left before penetration zero. When he awakes, the Doctor goes to the main control room and tries to smash the controls. He is unsuccessful and has to be restrained, but manages to tell Liz to put a new circuit into the computer that Stahlman had sabotaged. Liz does so, and the computer advises drilling be stopped at once. In the meantime, Stahlman orders everyone out of the drill head area, then when they are gone he picks up a handful of slime and rubs it into his face, causing himself to completely mutate. The Doctor escapes from the sickbay and returns to the control room, dealing with the Bromley mutant on the way. The Stahlman mutant emerges and has to be subdued with fire extinguishers. With seconds to go, the drill is shut down. The Doctor recommends to Sir Keith that arrangements be made for the shaft filled in.

Later, Sir Keith, who suffered only minor injuries in the crash, informs the Doctor that the project is being abandoned and everyone is leaving. The Doctor announces that he, too, is leaving. The Brigadier and Liz protest, and the Doctor sharply tells the Brigadier that he reminds him of his fascist counterpart. The Doctor activates the console and vanishes; on this occasion, Bessie is left behind. A few minutes later, the Doctor appears at the door of the hut, with mud on his clothes – having only made it as far as a nearby garbage dump. Suitably chastened, he asks the Brigadier to help him retrieve the console: it has landed in a somewhat inaccessible position, much to Liz's amusement.

Cast

 * Dr. Who — Jon Pertwee
 * Liz Shaw / Section Leader Elizabeth Shaw — Caroline John
 * Brigadier Lethbridge-Stewart / Brigade Leader Lethbridge-Stewart — Nicholas Courtney
 * Sergeant Benton / Platoon Under Leader Benton — John Levene
 * Professor Stahlman / Director Stahlman - Olaf Pooley
 * Sir Keith Gold — Christopher Benjamin
 * Petra Williams / Dr Williams - Sheila Dunn
 * Greg Sutton / Greg Sutton (Inferno Earth) - Derek Newark
 * Private Latimer - David Simeon
 * Private Wyatt - Derek Ware
 * Harry Slocum - Walter Randall
 * Bromley - Ian Fairbairn
 * RSF Sentry - Roy Scammell
 * Patterson - Keith James
 * Primords - Dave Carter, Pat Gorman, Walter Henry, Philip Ryan, Peter Thompson

Production crew

 * Writer - Don Houghton
 * Action / Stuntwork - HAVOC
 * Assistant Floor Manager - Sue Hedden
 * Costumes - Christine Rawlins
 * Designer - Jeremy Davies
 * Film Cameraman - Fred Hamilton
 * Film Editor - Martyn Day
 * Film Sound - Graham Hare
 * Make-Up - Marion Richards
 * Production Assistant - Chris D'Oyly-John
 * Script Editor - Terrance Dicks
 * Special Sounds - Brian Hodgson
 * Studio Lighting - John Green
 * Studio Sound - John Staple
 * Theme Arrangement - Delia Derbyshire
 * Title Music - Ron Grainer
 * Visual Effects - Len Hutton
 * Producer - Barry Letts
 * Director - Douglas Camfield

Locations

 * Sutton was flown in from Qatar.

The Doctor's items

 * Bessie travels with the Doctor and the TARDIS console into the parallel universe.

Theories and concepts

 * The Doctor claims a dimensional paradox would result from bringing anyone from the parallel Earth back to Earth's universe.
 * The Doctor refers to this travel to an alternate universe as travelling "sideways" in time.
 * Events in the other world are running ahead of the "regular" Earth (Sir Keith's accident, Penetration Zero etc).
 * The Doctor sarcastically wonders whether Sutton was expecting his TARDIS console to be a space rocket with Batman at the controls.

Individuals

 * The Doctor met King Edward VII in Paris. He states he was at Krakatoa during the eruption of 1883, during which he heard the screeching sound the Primords made, implying that he had encountered (or at least heard) the creatures before.
 * The Doctor is the only individual in this story to not have a counterpart in the parallel universe. Although it was later confirmed that the Leader, an individual seen in a picture behind the Brigade Leader was the parallel Earth's version of the Doctor.

TARDIS

 * The TARDIS console is removable and can travel by itself, although it needs an external power source to do this.

Tools

 * Slocum murders a technician with a wrench.

Songs from the real world

 * While driving Bessie, the Doctor sings an excerpt of the song La donna è mobile.

Story notes

 * This story had the working titles of The Mo-Hole Project, Operation: Mole-Bore, The Mole-Bore and Project Inferno.
 * The primordial mutant creatures are named "Primords" in the closing credits of episodes five and six and publicity material, but are left unnamed in the story's dialogue.
 * The opening credits for this serial were unusual in that after the initial titles, the name and part number of the serial were superimposed on footage of a lava flow, with no music.
 * The Radio Times programme listing for episode one was accompanied by a black and white rehearsal shot of the Doctor standing at the TARDIS console, with the accompanying caption "Knock, knock. Who's there? 5.15", while that for episode seven was accompanied by a black and white photograph of the mutated Director Stahlman, with the accompanying caption "Meeting the Primord. Dr. Who: 5.25".
 * In spite of Douglas Camfield receiving sole credit as director, the second studio recording block and studio blocks 3 & 4 were directed by producer Barry Letts after Camfield had a minor heart attack on 27 April 1970. Letts later stated that Camfield's preparations for episode one's studio recording were so meticulous that he just followed Camfield's existing camera script. For the other episodes, Letts worked to his own plans, which he had to hurriedly construct. In the end, Camfield directed all the location filming and designed the direction executed by Letts on episode one's studio recording. Nevertheless, Camfield remained credited as director, as BBC regulations at the time forbade the same person being credited as producer and director.
 * Derek Ware did not perform the scene where the mutated RSF Private Wyatt is shot and falls to his death from the top of one of the cooling towers, in case he was injured, as he was also needed for studio recording. His place was taken by Roy Scammell who, curiously, also played the RSF sentry who fires the fatal shot. Ware stated in an interview that Scammell had already signed the contract to do the fall before Ware had been cast as Wyatt.
 * The role of Petra was given to Sheila Dunn (Douglas Camfield's wife) after Kate O'Mara was not available to play the part. O'Mara would, years later, be cast as the Rani, a renegade Time Lord.
 * Episode six has a small damaged section on the tape, which the Doctor Who Restoration Team replaced by painstakingly recolouring the appropriate section of the existing 16mm black & white film telerecordings.
 * Caroline John enjoyed her role as Section Leader Elizabeth Shaw and says that it was fun playing 'baddie' Liz. She also says she hated doing the scenes when she was playing the 'goodie' version because it was boring compared to being an evil character. She was particularly upset though about the scene in which Shaw shoots Brigade Leader Lethbridge-Stewart, as she was pregnant at the time. As a result, the scene was recorded with the weapon fired from out-of-shot, after which Shaw was shown returning the gun to her holster.
 * Nicholas Courtney has also said he enjoyed playing the parallel version of the Brigadier. He called it his "favourite" in an interview with Doctor Who Magazine in 2009. The DWM staff remembered this by including it in his tribute issue as that month's "The Fact of Fiction".
 * At Doctor Who fan events, Courtney frequently recounted an incident which occurred during shooting of the scene with the revelation of the Brigade Leader and his eyepatch. The scene begins with Courtney having his back to the camera (and to all the other actors), before spinning around in his swivel chair to reveal the Brigade Leader's visage and eyepatch. When the scene was shot, Courtney spun around to discover that all the other actors and crew members were also wearing eyepatches. According to the story, he then proceeded to perform the entire scene as if nothing unusual had occurred. The "eyepatch story" became so closely associated with Courtney that Steven Moffat wrote scenes in which "everybody was wearing an eyepatch" into the 2011 episode The Wedding of River Song as a tribute to Courtney, who had died earlier that year. (DWMSE 31)
 * During the scenes set on the parallel Earth, images (supposedly) of the UK's dictatorial leader are seen on posters. The image used is that of visual effects designer Jack Kine, in homage to the 1954 BBC adaptation of George Orwell's where the face of Big Brother was Head of Television Design Roy Oxley (Kine had worked on the visual effects for that production).
 * Inferno marks the first story in Doctor Who to be set in a parallel universe.
 * The scenes on top of the nuclear reactor in episode two were not easy for Jon Pertwee, as he was afraid of heights. It took him fifteen minutes just to summon up the confidence to film the scene.
 * In episode three, during the chase scene on the parallel Earth, Bessie's bumper gashed open stuntman Alan Chuntz's leg as it passed. The gash was so severe that he had to go to A&E. Barry Letts stated on the DVD commentary that "it was the worst wound [he]'d ever seen" and after Pertwee saw the wound and learned he caused it, he became sick and almost couldn't carry on filming until a few hours later. Jon Pertwee even went as far as buying Chuntz's wife a gift to apologise for the accident.
 * A Doctor Who Unbound story would later touch on a narrative element of this story. According to Sympathy for the Devil — a narrative not part of the Doctor Who universe —research into the possibilities of Stahlman's gas was still ongoing in 1997, the year that the Doctor in that continuity's exile on Earth began.
 * This was the final story to feature the original TARDIS console prop. Having been in use since the show's first episode in 1963, the prop had gradually deteriorated over the years, with numerous bits and pieces falling off or being replaced. After this story aired, the prop was deemed unusable and junked. For the TARDIS console unit's next appearance in The Claws of Axos, a new prop, designed by Kenneth Sharp, was built.

Ratings

 * Episode 1 - 5.7 million viewers
 * Episode 2 - 5.9 million viewers
 * Episode 3 - 4.8 million viewers
 * Episode 4 - 6.0 million viewers
 * Episode 5 - 5.4 million viewers
 * Episode 6 - 5.7 million viewers
 * Episode 7 - 5.5 million viewers

Myths

 * The parallel universe aspect of the story was added to the scripts at the production team's suggestion to ensure that there was sufficient material to fill seven episodes. (Though Terrance Dicks has claimed this in several documentaries, the parallel universe aspect was present as far back as Don Houghton's original story outline. It actually appears to have been the Primords who were added at the production team's suggestion)
 * This was Caroline John's last story as Liz as she was pregnant and could not return for the following season. (Although it is true that the actress was pregnant, Barry Letts was unaware of this when he decided against renewing her contract.)

Filming locations

 * Kingsnorth Industrial Estate (formerly Berry Wiggins and Co Ltd), Hoo St Werburgh, Kent
 * Ealing Television Film Studios, Ealing Green, Ealing
 * BBC Television Centre, Shepherd's Bush, London

Production errors

 * On the Nuclear Output Gauge in the Doctor's workshop, Mega-volts is spelled 'Megga Volts'.
 * Whilst the Doctor ponders a way of escaping the Primords with a single fire extinguisher, another can clearly be seen on the wall beside him.
 * During some shots of episode six when Sutton is holding off the Primords with coolant from a fire extinguisher, none is actually coming out of the nozzle.
 * In episode seven, the dead Primord Stahlman has a little bit of human skin poking out of his neck.
 * Director Stahlman is seen to wear a nameplate that reads STAHLMANN, but he is actually credited on-screen on 'Director Stahlman'.
 * In episode seven, while the Doctor is stopping the drill, Caroline John's floor-marker is clearly visible.

Continuity

 * PROSE: Timewyrm: Revelation states that the dictator was one of the alternative regenerations the Time Lords offered the Doctor in TV: The War Games.
 * Liz Shaw does not feature in any subsequent serials, although an illusory image of her is seen in TV: The Five Doctors (and the character is one of many in TV: Dimensions in Time). The circumstances surrounding her departure from UNIT are told in PROSE: The Scales of Injustice. In the next serial (TV: Terror of the Autons) it is merely mentioned that Liz went back to Cambridge.
 * PROSE: The Face of the Enemy is a sequel to Inferno, revisiting the 'alternate' world.
 * PROSE: Still Lives features a UNIT corporal who becomes affected by the events of this story.
 * In 2007, the Doctor would travel to another parallel universe in which there is a Republic of Great Britain. (TV: Rise of the Cybermen / The Age of Steel)
 * A sketch that washed up on the shores of Sumatra following the Krakatoa eruption was later shown to Rose Tyler, depicting the Ninth Doctor in front of a volcano. (He may well have been in a different area near the vicinity of Krakatoa than his previous self.) (TV: Rose)
 * Also during the Krakatoa eruption, the Xylok which became Mr Smith was unearthed. (TV: The Lost Boy)
 * Another great drilling project into the Earth's crust was started in the Welsh village of Cwmtaff in the year 2020. (TV: The Hungry Earth)
 * The Eleventh Doctor later sang "La donna è mobile", again with altered lyrics, while in the shower in TV: The Lodger.
 * In February 1970, the journalist James Stevens dismissed Greg Sutton's outlandish claim that a green slime from the centre of the Earth transformed scientists into wolf monsters during the Inferno Project. He described Sutton's story as sounding like the plot of a "science fiction potboiler." (PROSE: Who Killed Kennedy)
 * After the failure of the Inferno Project, among other incidents, was publicised by James Stevens in his "Bad Science" series of articles in the Daily Chronicle, Harold Wilson's position as Prime Minister of the United Kingdom became untenable and the Labour Party lost the general election in June 1970 to the Conservatives, led by Edward Heath. (PROSE: Who Killed Kennedy)
 * By 1973, Sutton had befriended the First Doctor's former companion Ian Chesterton. (PROSE: Byzantium!)

DVD releases
This story was released as Doctor Who: Inferno.

Released:
 * Region 2 - 19 June 2006
 * Region 4 - 6 July 2006
 * Region 1 - 5 September 2006

Contents:
 * Commentary by Nicholas Courtney, Barry Letts, Terrance Dicks and John Levene.
 * Can You Hear the Earth Scream? - A 35-minute documentary that looks at the making of Inferno. With contributions from Caroline John, Nicholas Courtney, John Levene, Ian Fairbairn, Barry Letts, Terrance Dicks and Derek Ware.
 * The UNIT Family (Part One) - A 36-minute documentary that looks at the role of UNIT in the world of Doctor Who through to the end of Jon Pertwee's first year as the Doctor.
 * Deleted Scene - A 2-minute scene cut from the original UK transmission of episode five, but which was retained for overseas screening.
 * Visual Effects Promo Film - An excerpt from a BBC Visual Effects Department showreel.
 * The Pertwee Years - Introduction - Jon Pertwee's original introduction to the final episode of this story.
 * Radio Times Billings - Articles and listings from Radio Times (DVD-ROM PC/Mac).
 * Doctor Who Annual 1971 (DVD-ROM).

Notes:
 * Editing for the DVD release was completed by the Doctor Who Restoration Team.

DVD special edition
Inferno has been re-released as a special edition in 2013.

Digital releases

 * Is available in BBC Store.
 * Was available for streaming in the US through Hulu Plus until early 2016.

Video release
This was released as a double-cassette pack on VHS in the UK in episodic format in March 1994, including in episode five the scene not shown on the original UK transmission (see DVD releases above).