4J. The Android Invasion

Season Thirteen - 1975/1976

Script Editor: Robert Holmes
Writer: Terry Nation
Produced by: Philip Hinchcliffe
Director: Barry Letts
Designer: Philip Lindley
Incidental Music: Dudley Simpson
Fight Arranger: Terry Walsh


The Doctor is trying to return Sarah to Earth. The temporal co-ordinates are set, but the linear calculator isn't right. The TARDIS over due a 500 year service, after all. The TARDIS, however, does appear to have landed on the Earth. As they are trying to find out where they the Doctor and Sarah come across four helmeted figures dressed in white. As they run from the figures Sarah trips and falls, and ends up hanging over the side of a quarry.

The Doctor rescues her, and they see a UNIT soldier heading towards the same quarry. They call out, but the soldier ignores them and plummets over the edge. They scramble down to the soldier but find him dead. The Doctor looks in his wallet for identification and finds, oddly, a collection of coins that are all new, and were all minted on the same date.

Moments later two of the helmeted figures starts firing at them, and the Doctor and Sarah run from the quarry, and find themselves in a small village Sarah recognises as Devesham. The village is empty; even the Fleur de Lys pub is empty, although there are half empty glasses on the tables. The Doctor examines the cash register and finds more freshly minted money of the same year. Sarah tells the Doctor she was once at Devesham because of a story relating to the Space Defence Station about a mile away.

One speculation is that an radiation could have leaked from the Space Defence Station leading to the village being evacuated in a hurry. The figures could have been guards, and he soldier could have been affected by the radiation. Looking out of the window Sarah sees the figures walking through the village, with the soldier. As they get close to the pub she ducks out of the way and knocks a glass of a table.

The smash alerts the figures, and they are about the enter the pub when a pick-up arrives with villages sat silently in the back. When the pick-up stops the villagers step of and silently head towards different buildings. Sarah recognises one of them as Mr. Morgan, the pub landlord. The Doctor and Sarah hide as the landlord, the soldier, and more villagers enter the pub. They remain motionless until a clock chimes, and they all start talking and drinking.

The Doctor tells Sarah to stay at the pub whilst he goes to the Space Defence Station to contact UNIT. He leaves Sarah with the TARDIS key, and tells her to return to the TARDIS if anything goes wrong. As the Doctor leaves Sarah accidentally knocks a door, and the soldier notices. All the villagers become silent again, apart from the soldier who wants to know starts to ask Sarah questions about who she is, and how she got there.

Morgan thinks Sarah may be part of the "test", but Corporal Adams doesn't think Sarah knows anything, and she is allowed to leave. As she does she sees one the figure that had driven the pick-up. It's helmet is open, and inside is electronic circuitry. The figure watches as Sarah runs back to the TARDIS. As she is opening the door she notices a strange pod outside. As she investigates the TARDIS de-materialises with the key still on the lock. She thinks it the Doctor leaving without her. She doesn't notice the pod open until a hand reaches out and tries to grab her. The pod opens revealing a man inside.

At the Space Defence Station the Doctor finds another UNIT soldier, but he completely unresponsive to the Doctor. In the Space Defence Station complex Senior Defence astronaut Guy Crayford is called by his superior, Styggron, to say that movement has been detected within the complex. He leaves his office to go and look, and misses the Doctor who enters his office - even though on the door is says "Brigadier Lethbridge-Stewart". Inside the Doctor is expecting to find the Brigadier. Moments later Crayford enters, armed.

The Doctor escapes to the roof where UNIT soldiers start firing at him, and he is caught by more helmeted figures. Sarah make her way to the complex in time to see the Doctor taken away, and she follows, and lets the Doctor out of the room he has been left in. Hiding in a cupboard the Doctor mentions Crayford to Sarah, who tells him that Guy Crayford was killed. He had been a test pilot of the XK-5 space freighter when his ship vanished in deep space.

Styggron demands to know about the second "random unit" from Crayford, and he tells Styggron about the Doctor and his human companion. Styggron demands that the Doctor and Sarah be recaptured for pattern analysis.

The Doctor and Sarah escape from the complex, but not before being noticed by Sergeant Benton, who does not seem to recognise them. UNIT soldiers, with dogs, head off on pursuit. Whilst escaping Sarah trips and injures her ankle. The Doctor helps her into a tree, and continues without her, taking her scarf to try and lead the dogs after him and away from Sarah.

Further on the Doctor leaves his jacket, scarf and shoes, and Sarah's scarf, besides a lake, leaving the UNIT soldiers to assume he and Sarah swum across. The Doctor had, instead, been hiding in the river. As the soldiers doubled back to go around the lake they re-capture Sarah as she gets down from the tree. Sarah is taken to an alien control room for brain analysis - performed by Harry Sullivan.

Back at the village the Doctor tries to use a telephone box to call for help, but the telephone does not work. He tries the telephone in the pub, but that also does not work. Shortly afterwards the telephone rings, and the call is for the Doctor. It's Sarah, saying she now knows their whole plan, and that she is at the village shop as the pub is not safe, and tells the Doctor how to get there. When the Doctor tries the telephone after hanging up he finds it dead again.

In the shop the Doctor meets Sarah, and she tells the Doctor about the fake Harry that she met. She tells the Doctor that people are being copied and replaced with duplicates. The Doctor realises that he is being tested. They return to where the TARDIS should have been, and the Doctor then realises what has happened. When Sarah put the key in the lock it cancelled out a pause control, and the TARDIS resumed course to Earth. The planet they are on is not Earth, and Sarah is not the real Sarah, as she is wearing a scarf, and didn't realise the TARDIS was missing.

In the alien control centre Sarah has been kept alive, and returns to consciousness in time to hear that the Kraals plan to destroy the village, and the Doctor, in nine minutes time. She also overhears them talking about a virus that they want to test on a living specimen. As the Kraals leave she sneaks out of the control centre.

In the village the Doctor watches as the village androids are taken back to the control centre by the white androids. What he doesn't see, until it is too late, is Styggron. Styggron overpowers the Doctor, and with the help of androids, ties him to a monument in the centre of the village along with an MD bomb that will, in three minutes, destroy he village.

Sarah gets to the village in time to rescue the Doctor for a second time that day. They make it out of the village, and into the alien control centre, just as the bomb explodes, where they are caught by Crayford, who orders androids to take then to a cell.

In the cell the Doctor explains to Sarah about the villagers, and Benton and Harry, all being android duplicates, and the fact that they are not on the Earth, but on the highly radioactive planet of the Kraals, Oseidon. It is because of the radiation that the Kraals are planning to invade Earth.

The Doctor has a plan to electrocute an android and escape, but before he can do so he is taken to the analysis chamber, but not before giving Sarah a hint about his plan, which involves using water that has been given to them. The plan works and Sarah escapes from the cell. Randomly trying controls Sarah rescues the Doctor from the analysis machine.

Part of the Kraals plan involves using Crayford's ship to return to Earth. He has already radioed Earth to let them know that after two years he has survived, and not died as previously thought, and the Space Defence Station on Earth is now expecting him back. The Doctor and Sarah manage to get on board his rocket before it leaves Oseidon for Earth.

On board the rocket are more of the pods. They are due to be fired towards Earth before roket arrives, and the Doctor and Sarah will be on board them. Only one of the pods already contains a Doctor android.

In the Space Defence Station on Earth the staff in the scanner room detect Crayford's XK-5 returning to Earth. The scanners also detect the pods being sent to Earth, but dismisses them as a meteorite shower. The pods have landed over a wide area, and when the Doctor leaves his pod he cannot find Sarah's pod anywhere close by.

Sarah makes it out of the pods, but can't find the Doctor's. She does find the TARDIS, though, and think the Doctor may be inside. As she looks inside the Doctor taps her on the shoulder. When she sees another Sarah behind him she realises he is not the real Doctor.

The real Doctor makes his way to the scanner room in the complex and meets the real Benton. He tells the people, including the real Harry Sullivan, not to enter the rocket and to return to the scanner room. The Doctor tells the scanner controller, Grierson, to reprogram the satellite dish to point downwards at the Defence Station.

The Doctor talks to the Defence Station commander, Colonel Faraday, but finds he is an android. As is Harry, and the android Doctor is there. The real Doctor manages to escape, with help from Sarah. The real Doctor makes his way back to the scanner room, followed shortly by the android Doctor. As the android Doctor aims a gun at the real Doctor Crayford interrupts. Crayford says Styggron promised there would be no killing, and the android Doctor tells him about the virus the rocket is carrying that can destroy all human life on Earth.

The android Doctor is distracted, and the real Doctor kicks away the gun and the two Doctors begin to right. The Doctor manages to hit the radar control, and the energy from the radar causes all android to seize up.

Sarah makes her way into the rocket where she finds the real Harry and Colonel Faraday tied up. She also encounters Styggron, who has the virus. As he is about to use it a reprogrammed android Doctor appears and attacks Styggron, who falls onto the virus container and ingests all the virus, killing him. Styggron shoots the Doctor, destroying the android.

Regular Cast

  • Sarah Jane Smith: Elisabeth Sladen

Guest Cast

  • Guy Crawford: Milton Johns
  • Styggron: Martin Friend
  • Corporal Adams: Max Faulkner
  • Morgan: Peter Welch (1-3)
  • Harry Sullivan: Ian Marter (2-4)
  • RSM Benton: John Levene (2-4)
  • Marshal Chedaki: Roy Skelton (2-3)
  • Kraal: Stuart Fell (3)
  • Colonel Faraday: Patrick Newell (4)
  • Matthews: Hugh Lund (4)
  • Grierson: Dave Carter (4 - also credited for 1 but does not appear)
  • Tessa: Heather Emmanuel (4)
  • Android Mechanics: Derek Hunt (1-3), Roy Pearce (1-3)
  • Farmer: Walter Goodman (1)
  • Young Farmhand: Simon Christie (1)
  • Barmaid: Margaret McKenchie (1)
  • Tweedy Doctor: Freddie White (1)
  • Students: Martine Holland (1), Mark Holmes (1)
  • Double for the Doctor: Terry Walsh (2-4)
  • Stuntman/Soldier: Peter Brace (2)
  • Villagers: (all 3) Keith Ashley, Barbara Bermel, Martine Holland, Cy Town
  • Soldiers: Mark Allington (2-3), Alan Clements (1-3), Alf Coster (2-3), Derek Hunt (3), Richard King, Pat Milner (3), Roy Pearce (3), Christopher Woods (2)
  • Walk-Ons: Lewis Alexander (1), Keith Ashley, George Ballantine (1), Simon Christie (3), Ian Elliott (1), Alan Jennings (1), Henry Lindsay (1), Sue Manners (1), Clinton Morris (1-3), Terry Walsh (2), Betsy White (1), Joan Woodgate (2)

Original broadcast on the BBC

Channel Title Date Viewers Rating
BBC 1 414. Part One Saturday, November 22, 1975 5:45 PM - 6:10 PM 11.9M 58%
BBC 1 415. Part Two Saturday, November 29, 1975 5:45 PM - 6:10 PM 11.3M
BBC 1 416. Part Three Saturday, December 6, 1975 5:45 PM - 6:10 PM 12.1M
BBC 1 417. Part Four Saturday, December 13, 1975 5:45 PM - 6:10 PM 11.4M


  • Television Centre Studio 3
  • Television Centre Studio 8

Outside Locations

  • National Radiological Protection Board, Harwell, Didcot
  • Worsham Quarry, nr. Witney, East Hagbourne, Oxfordshire


Part 1: There's a scene where the mechanics are shooting at the Doctor and Sarah, and they dive for cover behind a "meteorite". In the shot when they later run for it, you can see a tarpaulin spread behind the meteorite.

Part 1: While the Doctor and Sarah are walking through the forest (after they leave the clearing which the TARDIS is in) the Doctor pulls a branch out of his way. Lis Sladen isn't paying close attention and is in the middle of her line when the branch flies back and hits her in the face. You can tell she was stung a little because she gives a little squeak but manages to finish her line.

Part 1: The Doctor's scarf gets caught in the bushes and branches while walking along with Sarah, and Lis Sladen clearly laughs out of character.

Part 1: When Tom Baker arrives at the Space Defence Centre he asks a stony-faced android guard where the commanding officer can be located. The guard obviously has his pause button pressed, and is unresponsive - except for an uncontrollable blink as Tom moves away.

Part 2: Tom Baker throws the android Sarah to the ground at the episode's climax, and her face plate falls off to expose her electronic innards. The fake hair adorning its head is appallingly obvious, being a completely different texture and shade to Lis Sladen's own hair.

Part 4: When the Doctor comes through the automatic doors of the real Space Defence Centre for the first time they slide open, but not quite closed. The poor souls in charge of making them slide don't notice.

Part 4: In the fight scene between Tom Baker and his stunt double android the wig choice for his double leaves a great deal to be desired.

Part 4: When Tom Baker's android double is finally destroyed at the end its skin disappears to reveal the metal skeleton beneath. However the skeleton is actually larger than Tom's face; watch his left cheek.

Working Titles

The Enemy Within

Return to Sukkanan

The Kraals