The Ambassadors of Death (TV story)

The Ambassadors of Death was the third story of Season 7. It was the Third Doctor's first adventure into space without the use of his TARDIS. It also featured the first instance the TARDIS console was shown in colour format, and for that matter, removed from the TARDIS entirely. The Doctor had disconnected it and moved it to a study room inside UNIT headquarters now that his TARDIS was rendered inoperative, needing to utilise it in his experiments.

Synopsis
The Doctor joins UNIT's investigation of the mystery surrounding Mars Probe 7. Space Control, headed by Professor Ralph Cornish, has had no contact with the astronauts on board since it started back from Mars seven months ago. Now the Recovery 7 rescue mission has run into similar difficulties.

This second ship gets back to Earth, but the astronauts are kidnapped after landing and Liz Shaw notices that the Geiger counter is at maximum. It transpires that the ship's occupants were not the human astronauts after all but a trio of radiation-dependent alien ambassadors who had swapped places with them.

The Doctor makes a solo flight in Recovery 7 and docks with Mars Probe 7, still orbiting in space. He is intercepted by a huge, alien spaceship and taken on board, where he finds the real astronauts unharmed. The aliens' captain threatens to destroy the Earth unless their three ambassadors are released.

The Doctor is allowed to go and, after returning to Space Control, discovers that the kidnapping of the ambassadors is part of a scheme devised by xenophobic ex-astronaut General Carrington to discredit the aliens and convince the world's authorities to wage war against them. The Doctor and UNIT thwart his plans and arrange the safe exchange of ambassadors for astronauts.

Episode 1
An astronaut is bearing down on Mars Probe 7. There has been no contact between the probe and Earth for seven months when it took off from Mars. The Brigadier, who is overlooking the proceedings in the Space Centre, asks Professor Cornish, who is running the recovery mission, if he considers them to be dead. Cornish says he suspects so. The whole recovery mission is being televised live.

The Doctor is trying to reactivates the Time Vector Generator using his TARDIS control. He inadvertently sends Liz fifteen seconds into the future before doing so to himself - much to her confusion. The Doctor notices the Brigadier on television. He is still bitter about the Brigadier's decision to destroy the Silurians. The Recovery Vessel is about to link up with the Probe.

The Brigadier asks the astronaut if he is sure the probe is Mars Probe 7. He says it is. He tries for radio communication one last time and them begins the process of linking up.

The Doctor watches, enthralled.

The astronaut activates the airlock. The air holds. He goes to open the hatch and bears something on the other side. He thinks he hears the hatch in the probe open. He opens his own hatch.

Communication is lost in the Space Centre. All they hear is a shrill noise that hurts the ears of everyone listening. When it is done their is no contact.



Back at UNIT headquarters, the Doctor recognises the sound but can't place from where. He and Liz set off for the Space Centre.

Cornish is told there is no issues with any of the equipment at the Space Centre so it must be an issue on the vessels. One of the other doctors, by the name of Taltalian, is being interviewed but gets frustrated with the journalist and walks off.

The Doctor drives into the Space Centre directly after another vehicle, much to the concern of the guards.

The probe is holding it's position. One of the scientists wonders if it was an excess of electricity built up in the probe that may have fried the communications but not killed the astronauts. The Doctor arrives being pursued by soldiers that are called off by the Brigadier. The Doctor says that the sound is a message. Cornish is dismissive of the Doctor but the sound returns. The Doctor identifies it as a series of high frequency accelerated impulses. He demands unlimited computer time and multiple copies of the recording so as to analyse it. Cornish's back is still up. The Doctor becomes more consolatory to him and he calms down. The sound appears again - but this time it is slightly different. The Doctor states it is a reply from Earth. He sets about coordinating a worldwide triangulation in expectation of a replay.

The broadcasters suggest that the noise is some kind of distress signal.

The Doctor is setting up the triangulation. Taltalian has set up another recovery probe that won't be ready for another ten days. Cornish is not happy with that and orders him to speed up or find another capsule from another country. Taltalian says there is no capsule ready in the world. The noise is replayed and the Doctor sets about collating the data. Loz receives some data from France which confirms that the signal is coming from London. The Brigadier gets UNIT to do a local triangulation which places it as emanating from an abandoned warehouse seven miles from where they are.

Two men are sending a message from the warehouse.

The UNIT forces arrive outside the warehouse.

The two men stop the signal and wait for a response. They know they will be being monitored but hope they won't be tracked. An associate of theirs called the Sergeant enters and says that UNIT forces have arrived. He is ordered to stall them but only kill if necessary.

A group of people, led by the Sergeant, hide from UNIT. The Sergeant fires his gun.

The two men send the signal again, confident that the Sergeant will hold them off.

The Sergeant kills one of the UNIT soldiers and a fire fight ensues. Many are killed as some of the Sergeant's associates join in. It soon becomes a hand to hand battle. The Brigadier stops the Sergeant from escaping. They face each other. Both pointing their guns at one another. A UNIT soldier approaches from behind the Sergeant and swings a heavy metal implement attached to the ceiling. The Sergeant dodges it and the Brigadier is disarmed. The Sergeant has a clean shot of the Brigadier. Instead he drops his gun and is led away.

The two men trigger the self destruct function on the machine they have been using. The men go through the window but not before they draw the Brigadier in by firing their gun. As the Brigadier enters the communication device explodes.

The Doctor complains to Cornish that Taltalian is refusing him use of his computers. Cornish contacts Taltalian and orders him to comply with the Doctor. Cornish is told by Athens that a solar flare is heading directly for where the probe is in orbit. Their controls are locked on manual and there is nothing that can be done. He contacts them imploring to unlock the manual setting.

On Mars Probe 7, Cornish's pleas echo round an empty cockpit.

The Doctor and Liz enter the computer suite only for Taltalian to emerge from behind the door and pull a gun on them.

Episode 2
Doctor Taltalian wants the tape. The Doctor asks if he understood the message and Taltalian says he did. The Doctor holds the tape out to Taltalian only to make it disappear. Taltalian searches the Doctor for it but is interrupted by the entrance of the Brigadier. Panicked, Taltalian takes Liz hostage until he can escape. The Brigadier pursues. The Doctor makes the tape reappear and explains to Liz that he transmigrated it but won't explain how. The Doctor and Liz find the analogue to digital converter. The Brigadier returns and says that Taltalian escaped. The Brigadier tells the Doctor about what happened at the warehouse and says they have taken prisoners. The Doctor wishes to talk to them.

The Doctor and the Brigadier interrogate the Sergeant but he won't talk. The Brigadier asks him why he didn't shoot him when he had the chance. The Doctor suggests he was ordered not to. The Brigadier tells the Doctor that they have no knowledge of the Sergeant- even the labels of his clothes have been removed. The Doctor realises that they are dealing with something larger than the Sergeant and goes to leave. Before he does he asks the Sergeant nicely if there is anything he can get for him before screaming at him like an army officer. The Sergeant springs to attention. The Doctor tells the Brigadier that the Sergeant is an army officer of some kind. A scientist comes to get the Doctor.

The TV broadcaster informs the public that the two capsules have separated but there is still no communication from either of the vessels.

The Doctor and the Brigadier return to be told that the vessels are seven miles apart and expanding. The Recovery Shuttle is heading towards Earth and is eleven minutes from re-entry. They are all surprised when the shuttle starts it's re-entry early. The Doctor leaves to check on Liz. The Brigadier leaves to run a security report on the Sergeant.

Unbeknownst to the Brigadier an anonymous figure disarms a UNIT soldier and frees the Sergeant.

Liz and another scientist called Dobson have found no pattern to the tape. The Doctor suggests there might be something wrong with the computer. Dobson is sceptical saying that the computer is infallible. The Doctor gets Liz to ask the computer what two plus two is. The computer responds with five. The Doctor says that Taltalian has sabotaged the computer.

The Recovery Shuttle is ten seconds from control range. Contact is established between the shuttle and the Space Centre but there is no response. The Brigadier is worried that the shuttle will burn up on re-entry. The Space Centre takes over control of the shuttle. Radar contact is made.

The broadcast tells the public that the capsule is on course to land somewhere in the South of England.

The Space Centre is tracking the capsule and controls its landing. Once it lands the Brigadier and the Doctor congratulate Cornish.

The Doctor, the Brigadier and Cornish go out to the capsule. Cornish speaks to the astronauts through a communication device on the outside of the shuttle. There is no response. Unbeknownst by them they are being watched by the men from the warehouse. Cornish wonders if the astronauts are unconscious and also tells the Doctor and the Brigadier that the mechanism is jammed or locked and that they can't cut into the capsule as it would be dangerous for the astronauts. The Brigadier suggest they take the capsule back to the Space Centre. The Brigadier contacts UNIT headquarters and orders that the route is cleared between where the capsule landed and the Space Centre. He also asks for police outriders to accompany them. They load the capsule onto the back of a tuck and head off. The Brigadier goes with the capsule in the truck whilst the Doctor goes separately in Bessie.

The Brigadier sees a helicopter in pursuit of the truck. It hovers over the tuck and drops smoke grenades which disorientate the driver and the outriders. The truck is forced to stop. The helicopter lands. A firefight ensues between the UNIT soldiers and the men in the helicopter who have alien weapons. Many UNIT soldiers are killed. One of the men takes off with the helicopter whilst two others, the ones from the warehouse, steal the truck.

The Doctor comes across the truck. He blocks the way with Bessie. The two men ask him to move but the Doctor takes on the role of a doddery old man whose car has broken down. He asks for their help in moving the car. The men get out and push Bessie to the side of the road. As they do the Doctor flocks an anti-thief device switch on the dashboard of the car which causes the outside of the car to become magnetised and glues the men to the car. The Doctor re-steals the truck.

The Brigadier is complaining to Cornish about the theft of the truck. He is flabbergasted to round the corner and see the Recovery Capsule being examined. The Doctor appears and explains what happened. He receives a phone call from Liz to say she has discovered the pattern. The Doctor leaves. Cornish continues connecting equipment to the capsule.

Liz shows the Doctor the pattern she discovered. It proves that Taltalian has been some kind of prior information regarding the situation. The Doctor heads off saying that he is going to go and talk to the "top man". Once alone, Dobson rings someone and informs them that the code is close to being cracked.

The Doctor and the Brigadier explain to Sir James, the Minister for Technology, everything that has happened and their theory that there is a mole. Sir James seems blasé and sends the two men away. The Doctor is cross but the Brigadier shuts him up. When the Doctor and the Brigadier leave he goes to his cupboard where Taltalian has been hidden.

There is no response from Recovery Shuttle 7. Cornish is preparing the thermal lances when Liz starts picking up some static.

Sir James and Taltalian discuss how the Doctor is getting closer to their secret. Sir James say they are soon going to get a surprise.

A voice comes from the shuttle. It is one of the astronauts asking for permission for re-entry. Cornish proudly tells them they are back at the Space Centre. The astronaut repeats his message for re-entry. He continues to repeat this message no matter what he is asked. The Doctor asks them to cut open the capsule.

Episode 3
The craft is opened, and found to be empty, save for a recording of the astronaut's voices and a high amount of radiation. Carrington has ensured the contents – three space suited astronauts – are detained elsewhere, feeding them radiation to keep them alive. Carrington is now introduced to the Doctor by Sir James Quinlan, the Minister for Technology, who explains that he is head of the newly formed Space Security Department, and that his actions were to protect the astronauts as they had been infected with contagious radiation. Quinlan states that they did not want the public to become panic-stricken so Carrington had been acting with authority in his actions. By the time Carrington takes the Doctor and his friends to meet the astronauts, the situation has changed again. A criminal named Reegan has organised their abduction, killing the soldiers and scientists protecting them. Two of his henchmen are ordered to protect the astronauts, but the radiation they emit later kills them. Reegan, suited in protective clothes disposed of their irradiated bodies in a Hertfordshire gravel pit, burying them under the rocks. He then returns to his laundry van. Covering his tracks with camouflage tactics, he pushes a dashboard button that flips over the van's number plate to another registration code. At the same time, the "Hayhoe Launderers Ltd" signage on the van changes to read "Silcock Bakeries". Later on, the worker manning the industrial shovel uncovers the bodies when sifting the gravel.

When the Doctor and Liz examine the situation they work out that human tissue could not have withstood the degree of radiation emitted to the astronauts, who are still in orbit, meaning the three space suits contain alien beings instead. Reegan and his own scientist, Lennox, a disgraced Cambridge professor, are keeping the aliens alive, thinking the radiation needs to disperse, but they are weakening. Reegan enters their locked chamber to check up on one that collapses, but the alien recovers, thrusts him into a wall, and attempts to escape. Lennox flees, running up to find the laboratory exit locked, nearly getting him killed by the advancing alien. It runs out of strength again and falls down the stairs before laying a hand on him. Reegan recovers from the attack, disregarding Lennox's anger about locking the door. They realise the aliens need radiation to survive and begin dosing them with isotopes.

In order to aid Lennox in maintaining the alien beings while they are incarcerated, Reegan lures Liz and the Doctor into the open by issuing a false announcement that the Brigadier wants them to examine the bodies of the radiation victims now uncovered in the gravel pit. The Doctor chooses not to go, wanting to ready Recovery 7 for another flight into space rather than wait for Recovery 8, as its radiation has dissipated. Soon after Liz departs, the Brigadier walks in unexpectedly and the Doctor learns he didn't send for them. Lethbridge-Stewart immediately gets after Liz, who is now on her way to Hertfordshire in Bessie. Another car staked out on a side road waits for her to pass, then takes chase from behind and Liz fights to stay ahead of it. However, the horsepower of the modern vehicle quickly outpaces the vintage car and overtakes Bessie on a straight patch of road. Liz is forced to stop and bail out in a sprint, where Reegan's henchmen attempt to capture her. The chase leads to a pier, where Liz fights off one man, but slips over a railing as another man grabs her by the legs, and she dangles helplessly above a death drop.

Episode 4
Despite Liz hanging off the edge of the bridge she does not evade her captors and is brought to the lab where the astronauts are being kept to help Lennox.

Carrington has issued a police alert for the return of Liz. He has also found some documents in a foreign language in the lab that, he thinks, proves that the astronauts have been stolen by a foreign country to be used as a weapon. The Doctor thinks that this is a plant and that the astronauts are still in space. He wants to decipher the impulses sent originally. Carrington says it is futile but that does not put the Doctor off.

Cornish and Taltalian are calculating how to get the capsule into space and are having to cut corners because of the blocks that Sir James is putting into place. The Doctor enters and he and Taltalian make up. Cornish asks after Liz and the Doctor says there is no news. He says that he wants to use the computers to try and find a pattern in the phone rings. It is for the Doctor. He is told that unless he stops interfering Liz will be killed. He hangs up and continues to decode the message.

Liz is helping Lennox. Lennox sends a guard out to tell Reegan there is only one canister left. Whilst the guard's back is turned Liz tries to run but the door is locked. When she returns she is scornful of Lennox's involvement in the project. He says he has nowhere else to go. As Lennox prepare to enter the quarantine, he hands Liz a key and tells her to lock him in the quarantine and run. She does so.

The Doctor has cracked the code. It is instructions to build an electronic device. He questions Taltalian and says he is still an informer.

Liz sneaks out and runs through the forest.

Taltalian is shocked that the Doctor has accused him. The Doctor says that he can either confess to him or he can be interrogated by the Brigadier. He leaves to build the machine. Left alone, Taltalian picks up a device and leaves.

Liz attempts to hitchhike. A car pulls over. It is Taltalian. He pulls a gun in her and tells her to get in. She is returned to the lab where she tells Reegan that the door was left open. Taltalian hands the device over to Reegan saying that the creatures will respond to the commands that are given to them and if they don't they can threaten to cut off their radiation. Taltalian says that Reegan is to conduct a series of raids on targets. Taltalian berates Reegan for calling the Doctor - saying that it only got his ire up and that he needs to put out of way before he constructs another one of the machines. Reegan says he will deal with it.

The Doctor tells the Brigadier about his suspicions regarding Taltalian- however he has no proof. The Brigadier is unsure but the Doctor says he doesn't believe any of it. The Doctor requests a list of equipment and leaves - not before asking of any news regarding Liz.

Lennox surreptitiously thanks Liz for not grassing on him. Liz is determined to escape again.

In another room, Taltalian is anxious to return. Reegan gives Taltalian a bomb to kill the Doctor with. He sets it for fifteen minutes but, while Taltalian's back is turned, changes it so it will explode straight away.



Cornish is frustrated. All available astronauts have been transferred by Sir James. The Doctor volunteers to pilot the capsule. Cornish questions whether he has the ability to do so. The Doctor says he has spent more time in space than all of his astronauts put together and can face any tests required. Taltalian returns and Cornish asks if he has the computations for the capsule left. Taltalian stalls him and Cornish leaves. The Doctor asks if he has thought of the deal he offered him. Taltalian says he will tell the Doctor everything if he allows him to get away. He says he needs to go to his car for the information. He sets the bomb which explodes instantly.

The device that Taltalian gave Reegan can control the astronauts.

The Brigadier and the Doctor pick through the debris in the lab. Taltalian is dead - betrayed by whoever gave him the bomb. The Doctor finds another one of the controllers in Taltalian's possession.

Sir James tells Carrington that he has done everything to block Cornish's flight but he can't delay anymore. Sir James suggest they tell the truth but Carrington says they cannot do that - despite the launch of the capsule leading to a disaster for the entire world.

Reegan shares his disappointment at the survival of the Doctor with a superior on the phone. Once he is off he calls for a van and says that the astronauts are going on an excursion. Reegan asks Liz if the controllers can go the other way and if the astronauts can communicate with them. Liz says that it is possible but something would have to be created.

Later an astronaut approaches a military base. A guard orders it to stop but it continues. The guard fires at the astronaut but it continues. The astronaut radiates the fence and kills the guard. The astronaut continues on and enters a workstation where he kills all the workers. He starts to search the workstation. A guard enters with a machine gun. The astronaut kills him.

The Doctor has discovered that the device translates alien impulses into human speech and wants to build the other part of the machine. The Brigadier says he is trying to deliver as much equipment as possible but they are coming from Japan. The phone rings. It is Sir James for the Doctor. He asks if the Doctor can be dissuaded from piloting the capsule. The Doctor says only if he is told the truth. The Doctor agrees and he and the Brigadier make their way to Sir James.

The astronaut enters Sir James' office. He is killed. The astronaut uses radiation to open the safe and destroys the contents. The Doctor enters and only sees Sir James dead. As he checks him over the astronaut approaches the Doctor from behind.

Episode 5
As the astronaut bears down on the Doctor, the Brigadier enters and shoots at it. The astronaut turns and rounds on the Brigadier. The astronaut escapes, killing a UNIT soldier as it leaves. It radiates the lock behind it as it goes, locking them in.

Liz speculates that the astronauts are not human and questions Lennox as to whether Reegan is in charge. Lennox tells her that Reegan answers to someone higher up. Liz tells Lennox she has a plan for him to escape.

The Brigadier shows the Doctor the bullets he fired at the astronaut. They are dented. The Doctor says they have been deflected off a kind of force field. A UNIT soldier says that there is strong traces of radiation leading outside the building and then it disappears. The Brigadier says this is proof that the astronaut was collected by a vehicle. The Brigadier wonders what the purpose of all this is and speculates if it is conquest. The Doctor states that this is what they are supposed to think.

The astronaut is returned to the lab.

Cornish is explaining the capsule to the Doctor. He explains that, due to the blocks already established before Sir James' death, they have had to mix standard fuel with a type of fuel name M3 which has never been done before. The Doctor's medical report is presented to Cornish. He seems confused by it but the Doctor swiftly moves on.

The astronaut collapses as soon as it is back in the quarantine. Lennox re-radiates it. Liz asks Reegan what it has been doing. Reegan explains it has been killing her UNIT friends. When he leaves Liz accuses Lennox of facilitating murder. Liz says that Lennox should go to the Brigadier and that she can help him talk his way out.

Carrington enters the Space Centre and tries to block the launch of the capsule. Cornish points out he does not have the rank to do that. Carrington says he is convinced that this is an alien invasion with the collaboration of a foreign power. The Doctor points out that this does not explain why he opposes it. Carrington says that he believes the capsule should carry a nuclear warhead instead. Carrington says he is going to take his objections to the highest level. Cornish says that he had better hurry as they will be launching in two hours.

The astronaut is recovering. Liz and Lennox are still squabbling. Liz tells Lennox to tell the guard he needs more isotopes and that he needs to see Reegan. Lennox tries this but is blocked. Liz fabricates a story about the astronauts dying and convinces the guard. He still does not let Lennox leave but Liz convinces him that the death of the astronauts will be on his hands. Lennox also adds that he is not a prisoner. The guard is convinced and frees Lennox.

The capsule is ready and the Doctor is summoned to the preparation room. The Brigadier asks the Doctor why the launch time has been brought forward. The Doctor explains it has been done to thwart Carrington. There is a call for the Brigadier. It is Sergeant Benton who says that a man named Lennox is desperate to see him and is frightened out of his wits. The Brigadier tells Benton to put him in a cell until he has a chance to speak with him.

Lennox is led to the cell and is unsure of its safety. He implores the guard to lock the door.

The Doctor is ready for the launch. The Brigadier says goodbye and the Doctor proceeds to the capsule.

Reegan is cross at the guard for letting Lennox go. The guard blames Liz. Reegan grabs her and puts his gun to her head, demanding to know where he went. Liz says he went to the Brigadier. Reegan rushes to the phone and calls someone. He says that they are to take care of Lennox while he will take care of the Doctor.

Cornish is performing an instrument check on the capsule. The Doctor is very I,patient and only gets more so when told he is still thirty three minutes away from launch. He is told that the fuel is taking a long time to load and that they have to get the balance between standard and M3 fuel just right otherwise the ship will blow up in orbit.

A man tries to infiltrate the Space Centre dressed as a mechanic. He knocks a guard unconscious and begins to climb the scaffolding around the launch site. He kicks a worker that tries to stop him off the side. He begins to turn valves around the launch pad.

A fuel injection malfunction registers in the Space Centre. Cornish is concerned but it soon self rectifies.

The man is till making his way around the launch pad, knocking out any workers that he comes across. He turns a large valve on a cylinder marked 'M3 Fuel'. He climbs higher and higher turning valves as he goes and then makes his escape.

Food is brought to Lennox. As the guard leaves he implores for the door to be locked. He takes the lid off his food and finds an isotope. Horrified he presses the panic button but there is no response.

The Brigadier finds the groggy soldier that the saboteur knocked out. He rushes out and investigates - seeing the damage he has left.

At the Space Centre they are all set for take off. The countdown begins when the Brigadier rushes in and orders the take off to be cancelled. Cornish ignore him and the rocket takes off.

The Doctor is sustaining huge amounts of G force and the rocket's speed is 20% higher than it should be. The fuel burn will not reduce and the Doctor is at risk of blowing himself out of Earth's orbit and into the Sun. Cornish implores the Doctor to try and control the fuel burn manually but the heat has corrupted the controls. The rocket's speed is now 37% higher than it should be. The Doctor tells Cornish to jettison stage one of the rocket but Cornish is reluctant to as it will mean the Doctor would struggle to get into orbit. The Doctor points out that it is the only option they have. Cornish orders the jettison. This stabilises the rocket and returns the speed to normal. The Doctor is informed of the saboteur.



Later Cornish is directing a very casual Doctor towards Mars Probe Seven. The Doctor links the capsule to the probe and unbuckled himself ready to move into the probe. Cornish urges caution but the Doctor is calm. As he opens the hatch Cornish warns of a UFO in collision with the Doctor and orders evasive action. The Doctor looks out the window and sees a large red disc approaching him.

Episode 6
The object is revealed to be an alien spaceship, which brings the Doctor aboard. Once there, the Doctor discovers the three original astronauts are unharmed but mentally deluded into believing they are in quarantine. An alien being now reveals itself to the Doctor and explains the humans are being held aboard the craft pending the safe return of the alien ambassadors. They had been sent to Earth following a treaty between the race and mankind, but the terms of this agreement have now been broken because of the detention of the ambassadors. The Doctor offers his personal guarantee to help return the ambassadors to their mother ship and resolve the conflict before a state of war is declared, and is permitted to leave the alien craft and return to Earth. When the Doctor touches down he is gassed and kidnapped by Reegan, who takes him to Liz. Reegan's real paymaster, the real organiser of the situation, is revealed to them: General Carrington. Declaring that he had intended Reegan to kill the Doctor, the General pulls a gun on him, declaring that killing him is his "moral duty".

Episode 7
Reegan convinces Carrington to spare the Doctor and make use of his scientific ability. The General reveals his actions have been prompted by xenophobia driven by his own encounter with the alien beings when he piloted Mars Probe 6 some years earlier. His co-pilot, Jim Daniels, was killed on contact with the aliens and the General signed the treaty with the aliens to lure three of their number to Earth, where he hoped he could unveil their real agenda of alien invasion. The use of the ambassadors to kill people was similarly done to arouse public opinion against them. The next phase of his plan is to force the ambassadors to confess their plot on public television. Leaving the Doctor and Liz working on a new and improved communication device to translate the aliens, Carrington departs for the Space Centre, where he aims to unmask the alien ambassador before the eyes of the world – and then call on the powers of the Earth to blast the spaceship from the skies. Using his work on the translator as a cover, the Doctor transmits a morse code SOS to the Brigadier's men. UNIT soldiers then raid the secret base and rescue the Doctor and Liz, apprehending Reegan and his thugs. The Doctor races to the Space Centre, and he and the Brigadier apprehend Carrington before he can make his broadcast. Carrington is taken away, protesting he was only following his moral duty. He asks the Doctor if he understands why he took such actions, and the Doctor sadly sympathises with the general, regretting that it came to this. The Doctor arranges for Cornish and Liz to send the ambassadors back to their own people, after which the three human astronauts will be returned. He says his goodbyes to Liz and the Brigadier, departing back to his UNIT laboratory.

Cast

 * Dr. Who - Jon Pertwee
 * Liz Shaw - Caroline John
 * Brigadier Lethbridge-Stewart - Nicholas Courtney
 * Ralph Cornish - Ronald Allen
 * Taltalian - Robert Cawdron
 * General Carrington - John Abineri
 * Van Lyden - Ric Felgate
 * John Wakefield - Michael Wisher
 * Miss Rutherford - Cheryl Molineaux
 * Grey - Ray Armstrong
 * Collinson - Robert Robertson
 * Quinlan - Dallas Cavell
 * Control Room Assistant - Bernard Martin
 * Dobson - Juan Moreno
 * Corporal Champion - James Haswell
 * Unit Sergeant - Derek Ware
 * Reegan - William Dysart
 * Lennox - Cyril Shaps
 * Heldorf - Gordon Sterne
 * Astronauts - Ric Felgate, Steve Peters, Neville Simons
 * Unit Soldier - Max Faulkner
 * Masters - John Lord
 * Flynn - Tony Harwood
 * Sergeant Benton - John Levene
 * Private Parker - James Clayton
 * Control Room Assistant - Joanna Ross
 * Control Room Assistant - Carl Conway
 * Technician - Roy Scammell
 * Alien Space Captain - Peter Noel Cook
 * Alien's Voices - Peter Halliday
 * Lefee - Steve Peters
 * Michaels - Neville Simons
 * Private Johnson - Geoffrey Beevers

Production crew

 * Action - HAVOC
 * Assistant Floor Manager - Margot Hayhoe, John Turner (both uncredited)
 * Costumes - Christine Rawlins
 * Designer - David Myerscough-Jones
 * Film Cameraman - A.A. Englander, Tony Leggo
 * Film Editor - Don Godden (episodes 1, 3-7), Chris Wimble (episode 2)
 * Incidental Music - Dudley Simpson
 * Make-Up - Marion Richards, Teresa Wright
 * Special Sounds - Brian Hodgson
 * Studio Lighting - Ralph Walton, Geoff Shaw, Dave Sydenham
 * Studio Sound - Gordon Mackie, Brian Hiles (both uncredited)
 * Title Music - Ron Grainer and the BBC Radiophonic Workshop, arranged by Delia Derbyshire (uncredited)
 * Visual Effects - Peter Day, Ian Scoones
 * Vision Mixer - John Barclay (uncredited)
 * Writer - David Whitaker, Trevor Ray (episode 1, uncredited), Malcolm Hulke (episodes 2-7, uncredited)
 * Script Editor - Terrance Dicks
 * Production Assistant - Nicholas John
 * Director - Michael Ferguson
 * Producer - Barry Letts

Story notes

 * Working titles for this story included The Invaders from Mars, Invaders from Mars and The Carriers of Death.
 * Part one of this story was the first time that the famous cliffhanger "sting" was heard at the end of the episode. However, it is actually not played under the cliffhanger as it would in years to come, but as an introduction to the credits. The following story, Inferno, would be the follow the same format. It would not be until the following season that the sting would be used in the most common form.
 * An unusual title sequence was used for this serial, with the sequence cutting off after the show's logo, repeating the previous week's cliffhanger, then returning to the titles for the serial's name, writer and episode number.
 * This was the last story written for Doctor Who by David Whitaker. It was his least favourite story, possibly because he ended up writing very little of it (see Writer credits above).
 * Apart from Brigadier Lethbridge-Stewart, who retained his regular uniform, all UNIT ranks wore new futuristic-looking uniforms which only ever featured in this story. The usual velcro-fastened jacket, shirt and tie were replaced on this occasion with a zip-up jacket without lapels worn over a polo-neck sweater.
 * The production text on The Ambassadors of Death DVD revealed that Reegan and his gang were originally Irish, and suggests it was changed after the Troubles started: "All in all, it might not have been the best moment to show Irish hoodlums planning to deploy a powerful new weapon."
 * The story was made entirely on 625 line PAL colour videotape. However, up until 2011, the videotapes of all bar episode one were lost (having either been erased for reuse or junked), and the story was only available as 16mm black and white film telerecordings. The only existing colour tapes of episodes two to seven were non-broadcast standard 525 line NTSC off-air video recordings recovered from Canada in the 1980s, with episodes two to four and six and seven having an intermittent fault with the colour signal — resulting in rainbow-like patterning being superimposed across the picture. Although episode five was successfully restored to colour, countless restoration attempts on the remaining episodes failed until the Restoration Team re-colourised the story using the technique they used on episode three of Planet of the Daleks.
 * The TARDIS console prop is shown for the first time outside of the TARDIS itself. Since the TARDIS had been temporarily "shelved" as a plot device, so had the elements of the console room set, which were placed in storage. The console was pulled out for studio recording in February 1970. Now seven years in use, it had suffered a degree of wear and tear, requiring the addition of replacement knobs and buttons for those that had fallen off. It would make its last appearance in the following serial, TV: Inferno before the prop's damage was diagnosed as extensive enough to warrant a redesign.

Ratings

 * Episode 1 - 7.1 million viewers
 * Episode 2 - 7.6 million viewers
 * Episode 3 - 8.0 million viewers
 * Episode 4 - 9.3 million viewers
 * Episode 5 - 7.1 million viewers
 * Episode 6 - 6.9 million viewers
 * Episode 7 - 6.4 million viewers

Filming locations

 * The exterior isotope factory scenes were filmed at Little Marlow Sewage Treatment Works.
 * Southall Gas Works in Middlesex and Blue Circle Cement Works in Buckinghamshire were used for the Space Headquarters.
 * Roads in Marlow and at the Marlow Weir were used for the chase sequences with Liz Shaw. Wycombe Air Park was used as Heldorf's lab, and Beacon Hill for Reegan's hideout.
 * Aldershot, Hampshire, warehouses on White Street, TCC Condensers in Ealing, and Folley's Gravel Pit at Spade Oak were also used.
 * All interior scenes were filmed at BBC Television Centre Studio 3.

Production errors

 * In episode one, when the video screen retracts, the CSO image stays still for several seconds, exposing it as an overlay effect.
 * At the climax at the end of episode one, the Doctor is confronted by Taltalian, who is wearing glasses and must pull his gun out of the waistband of his trousers. At the beginning of episode two, these glasses are gone and the gun is in Taltalian's hand from the start, revealing a mistake in the reprise following the end of filming for the previous episode.
 * In episode three in the scene where the Brigader, the Doctor and Liz first meet General Carrington, as he gets up from his chair and says "I'm sorry?" to the Doctor, a brief glimpse of a boom can be seen above his head.
 * In episode five, the word 'variant' — as in M3 variant — is spelt "varient" on location props. There is a close-up on one of the typos, where we see it rendered "M.3. Varient" — which raises the question: why is the number 3 written as an initial?
 * In episode four the Doctor has a stick-able plaster from the explosion blast, but in episode five after the recap, his plaster is gone with no explanation given for where it went.
 * The radioactive trefoil symbol is upside-down on all of the isotope canisters. The symbol should properly look like a black capital Y on a yellow background, not the other way round.
 * Taltalian's accent is French in the studio and British on location.
 * Recovery 7's nose changes colour between prop and model shots, with it being red on the model and grey on the prop.
 * Quinlan's office safe slips about as the alien tries to open the door. This is caused by the indelicate movements of a person tasked with special effects, who is hidden behind the safe, rigging the explosive effects for the moment the alien blows open the safe.
 * When the capsule is landing, it is moving across the map of the Atlantic far faster than the announcements indicate.
 * Liz Shaw's tights change colour from week to week despite the fact she's a prisoner.
 * The telephones on the desk where the Doctor sits to make the list of components he needs change position between episodes six and seven.
 * Max Faulkner's UNIT Soldier dies — and is actually scripted as dying — in episode four, but then mysteriously reappears at the end of episode six. He's not credited in the later episode, despite briefly speaking.  Given that INFO: The Ambassadors of Death reveals that episode six was edited in extreme haste, it's almost certainly a production error that Faulkner made it into the later episode.
 * In episode seven, when an ambassador attacks arriving policemen whilst Reegan steals radioactive isotopes, the actor's face can briefly be seen inside the suit in a close-up shot.

Continuity

 * The Doctor is still nursing a grudge against the Brigadier for blowing up the Silurian hibernation chambers in TV: Doctor Who and the Silurians.
 * The Mars Probe space program appeared in two novels. PROSE: Who Killed Kennedy revealed that the shuttles were developed from technology taken from International Electromatics.
 * In PROSE: The Dying Days it was revealed that the program was abandoned when Mars Probe 13 accidentally encountered the Ice Warriors and it was agreed that Earth would stay away from their territory.
 * TV: The Christmas Invasion also involves aliens attacking Earth after they intercept a probe sent to Mars, even though they are not from Mars themselves.
 * AUDIO: Red Dawn also features a manned mission to Mars.
 * Benton makes his first appearance since TV: The Invasion.
 * Taltalian and Quinlan received letters from the Apocalypse Clock which predicted the exact dates and times of their deaths. (AUDIO: The Last Post)
 * The Doctor mentions the Time Vector Generator component of his TARDIS is deactivated. By comments made by the Second Doctor, it would suggest that because the Time Lords disabled this component, his TARDIS interior will have reverted to that of a normal police box, no longer bigger on the inside. (TV: The Wheel in Space)
 * Furthermore, the TARDIS console has been ejected from the console room, but the First Doctor once indicated that it sealed away the heart and power source of the ship beneath its time rotor. (TV: The Edge of Destruction) One can surmise that because the Time Vector Generator is disabled, the interior of the TARDIS has likely changed and the power source could not escape, while the console itself could be ejected from the TARDIS to administer repairs.
 * The investigative journalist James Stevens and his wife Natasha Stevens watched Wakefield's reports on the Mars Probe 7 crisis on BBC3, as did millions of others across the United Kingdom. (PROSE: Who Killed Kennedy)

DVD
Originally planned for DVD release in 2011 alongside The Sun Makers, The Ambassadors of Death was delayed due to ongoing re-colourisation issues. These issues were resolved to the best of the Restoration Team's abilities in November 2011. The serial was released on 1 October 2012. The release is wholly in colour, with no option to see the parts that were monochromatic in the original VHS release.

DVD extras

 * Audio Commentary with actors Caroline John (Liz Shaw), Nicholas Courtney (Brigadier), Peter Halliday (alien voices) and Geoffrey Beevers (Private Johnson), director Michael Ferguson, script editor Terrance Dicks, stunt co-ordinator Derek Ware and stunt performers Roy Scammell and Derek Martin, moderated by Toby Hadoke
 * Mars Probe 7: Making The Ambassadors of Death with Michael Ferguson, Terrance Dicks, Derek Ware, Roy Scammell and assistant floor manager Margot Hayhoe
 * Tomorrow's Times - Third Doctor- Presented by Peter Purves
 * PDF Materials - Radio Times listings

BBC Store
This story was released in BBC Store, opened for UK residents on 5 November 2015.

VHS
This story was released on VHS in 2002 as a single selection, and in 2003 in the United States as part of the End of the Universe collection.

The story was released with over 90 minutes of the story in colour, and the remaining material in black and white — with subtle mixes between the colour and monochrome sections.

Episode one was taken from the original 625 line PAL colour videotape, episode four was black and white throughout, and episode five was a version with electronically restored colour. The remaining episodes were both colour and black and white.

Editing for the VHS release was completed by Doctor Who Restoration Team and also contains a black and white version of the trailer for the story before episode one and The Stages of the Restoration, a mini-documentary about the restoration techniques, after the last episode.

CD
A CD of the original television soundtrack was released in August 2009, with linking narration by Caroline John. This was an unusual move for BBC Audio, since typically they released soundtracks only for those stories which had missing episodes. This is one of the very few stories which visually exists in its (near) entirety to also get an audio release.