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From TARDIS Index File, the free Doctor Who reference.

"I just love clocks..."
―The Doctor
The Sontaran Experiment
Series: Doctor Who - TV Stories
Season Number: Season 12
Story Number: 77
Doctor: Fourth Doctor
Companions: Sarah Jane Smith

Harry Sullivan

Enemy: Field Major Styre
Setting: Earth, (possibly London)
Writer: Bob Baker and Dave Martin
Director: Rodney Bennett
Broadcast: 22nd February - 1st March 1975
Format: 2 25-minute episodes
Previous Story: The Ark in Space
Following Story: Genesis of the Daleks

The Sontaran Experiment was the third story of Season 12 of Doctor Who. Made entirely on location, it was the shortest story of the 1970s with only two episodes.



The Doctor, Sarah and Harry arrive on a desolate and apparently deserted Earth to discover that a group of shipwrecked astronauts from a human colony, GalSec, have been lured there by a fake distress call. One of their number, Roth, tells Sarah of an alien conducting gruesome experiments on him and his crewmates. The alien turns out to be a Sontaran, Field-Major Styre, who is compiling a report on human physical and mental capabilities as a prelude to an invasion of Earth.

The Doctor challenges Styre to unarmed combat. The Sontaran agrees but is quickly weakened in Earth's unfamiliar gravity. Harry meanwhile enters Styre's ship and uses the Doctor's sonic screwdriver to remove the vital terullian diode bypass transformer, so that when the alien returns there to revitalise himself he is drained of all his energy and destroyed.

The Doctor sends a message to the Sontaran fleet, warning them that without Styre's report they cannot invade.


Part 1

The Doctor and his companions arrive on Earth from Nerva Beacon

The Doctor and his companions Sarah Jane Smith and Harry Sullivan transmat down from Space Station Nerva to a field on the surface of the now-healed Earth. The Doctor starts on fixing the circle of transmat refractors with his sonic screwdriver while the others wander off to explore the surrounding area.

As Sarah and Harry walk across the plain, she hears a sound and sees some movement on the top of a hill. Harry dismisses it. Two men in spacesuits; Erak and Zake; are observing the Doctor through the crosshairs of their rifles. Erak leaves Zake to watch the Doctor while he reports the presence of the Doctor to another spacesuited man, Krans, who is tending a campfire. Meanwhile, Harry slips on the edge of a hole and tumbles down into it. He finds himself stuck, unable to climb out, as Sarah observes that the edge of the hole had been covered deliberately. Harry has no choice but to stay put as Sarah goes to fetch the Doctor.

Zake's observation of the Time Lord is interrupted by a strange floating robot drone that bears down on him. Zake flees, the robot pursuing him over the edge of a cliff. The Doctor finds Zake's body when Erak and Krans arrive. Thinking the Doctor has killed Zake, they stun him with their rifles before he can explain. As the two carry the unconscious Doctor away, they are being watched by yet another spaceman, Roth.

Sarah gets back to the circle, and finds the Doctor gone, his screwdriver abandoned. When Sarah returns to the hole, Harry is nowhere to be seen. Something had started throwing rocks down at Harry, and in scrambling for cover, he discovered a way out of the hole, climbing up through some rocks to the hills beyond. Sarah is about to climb down into the hole to look for Harry when Roth grabs her from behind, hiding her as the drone floats past. Once the danger is gone, Roth introduces himself to Sarah. He was the one who covered the edge of the hole, trying to trap the drone. He tells Sarah that the robot serves an alien who lives among the rocks, an alien who has tortured him and killed two others of his crew. Roth is obviously traumatised by his experiences, and vows he will not be captured again. When Sarah tells him about her friends, he informs her that the Doctor has been taken to the campsite.

At the campsite, Erak and Krans interrogate the Doctor, demanding to know what he has done to their crewmates. When the Doctor explains that he came down from Space Station Nerva, the spacemen (now joined by their leader, Vural) greet that news with great scepticism. Nerva is a mere legend, like Atlantis, the lost colony of mankind. The spacemen are from one of the other colonies, GalSec. The Doctor suddenly spots an odd looking button on Vural's suit, identifying it as non-human technology. The button is actually a remote camera, and somewhere else, everything is being observed by something with a grey, heavy, four-fingered hand.

Roth brings Sarah near the campsite, but refuses to approach: he tells Sarah that he saw Vural go to the rocks, and the alien let Vural go. The GalSec men tell the Doctor that a GalSec freighter had gone missing. Detecting a distress signal from the supposedly uninhabited Earth, they came to investigate, but their ship was vaporised when they emerged, leaving nine of them stranded. Then, the surviving crew began to vanish one by one. The Doctor offers to fix the transmat refractors and beam them all to Nerva where they can contact another GalSec ship, but Vural says that they are not taking orders from the "Old People". While the Nervans did nothing but sleep, the rest of mankind had spread across the galaxy and built an empire. At this point, Roth appears. While the three spacemen chase him, Sarah sneaks out from the rocks and frees the Doctor.

Roth loses the others, and meets up with Sarah and the Doctor. Sarah tells the Doctor about the robot, and the Doctor examines some residue on the ground, evidence of a terullian drive; except there is no terullian in this galaxy. The Doctor reasons that there must be some way out of the hole that Harry fell in, but as he climbs down, he too slips and falls to the bottom, losing consciousness. At that moment, the robot returns, and snares Roth and Sarah with cables.

Harry has made it to the hills, where he spots a man-sized metal sphere among the rocks. As he watches, the robot arrives with Roth and Sarah in tow. The sphere's door opens, and to Sarah's horror, out steps a Sontaran warrior.

Part 2

Styre examines the results of Experiment 5: Fluid deprivation

When Sarah expresses her disbelief, the Sontaran tells her he is Field Major Styre of the Sontaran G3 Military Assessment Survey, identical to the other Sontaran clone she encountered, but not the same. Roth cries out that he will not be tortured again, and makes a break for it, only for Styre to shoot him down. Roth had already been tested, so he was of no further use. Sarah, however, is far more interesting.

The three spacemen find the Doctor in the hole, but as they force him to climb out at gunpoint, the drone arrives and snares the trio. The Doctor goes back to the bottom of the hole, and finds the same exit that Harry used. Harry, in the meantime, finds another human chained to the side of the rocks, severely dehydrated. Nearby, Styre has Sarah tied up to the rocks as well, and has placed a device on her forehead. He seals her in with a force field.

Styre goes to his transmitter station and reports back to his Marshal. The Marshal is impatient for the intelligence report, but Styre tells him that some inconsistencies have arisen that he has to clear up before he submits it. Styre proceeds to subject Sarah to Experiment 7: resistance to fear. The device on her head begins to give Sarah hallucinations, and she starts to panic. The Doctor, however, has reached her and uses the sonic screwdriver to breach the force field. When he rips off the device on her forehead, she gives a scream and falls unconscious. The Doctor, enraged, attacks Styre, but the Sontaran easily fends him off. Styre shoots him when he runs, the Doctor collapsing in a heap.

Harry finds Sarah unconscious, and the Doctor's apparently lifeless body. The chained-up spaceman has also died of thirst, and Styre records the result of Experiment 5: human resistance to fluid deprivation. Harry prepares to attack Styre from behind, but is dragged back by the Doctor. Styre's shot had hit a piece of scrap metal the Doctor had taken from Nerva, saving his life. The Doctor tells Harry to look after Sarah while he discovers Styre's mission.

The robot brings the three remaining spacemen to Styre's ship, where it is revealed that Vural had tried to make a deal with Styre in exchange for his own life. However, Styre intends to experiment on Vural anyway, this time to determine the human ribcage's resistance to pressure and muscular strength. He forces Erak and Krans to hold a gravity bar above Vural's body, making it progressively heavier until it is all they can do to keep it from crushing Vural. Styre stops the experiment temporarily to go make another report, and the Doctor eavesdrops on it.

The Doctor sneaks away again, and meets Sarah and Harry. He tells them that Earth's galaxy has somehow become strategically important in the Sontarans' never-ending war against the Rutans, and Styre's experiments are to determine the physical limitations of humans, following which a Sontaran fleet will invade. The Doctor hatches a plan: he will distract Styre by challenging him to single combat. After a while, Styre will start to tire, and return to his ship to recharge his energy. While the Doctor fights Styre, Harry will go to Styre's ship and remove a key component.

The Doctor confronts Styre, lying to him that his experiments are useless: the spacemen are the human's "slave class", the weakest of them all. The Doctor, on the other hand, is representative of the warrior class. Styre accepts the Doctor's challenge, and while the two fight, Sarah and Harry free the three spacemen, then Harry climbs towards Styre's ship to carry out the Doctor's instructions. Styre nearly gains the upper hand, but Vural attacks him, saving the Doctor at the cost of his life. Styre, reaching his limits, heads back towards his ship. As the time travellers back away from Styre's ship, the Sontaran staggers out in pain, shrivelling up and deflating like a balloon before exploding. The Doctor explains that the device Harry removed sabotaged the energiser, so the energy fed on Styre instead of the other way around.

The Doctor makes his way to Styre's transmitter, and tells the Marshal that not only has Styre's intelligence mission failed, but that the invasion plans are in their hands, and if the Sontaran fleet moves across the buffer zone, it will be destroyed. The Marshal swears revenge, and terminates the signal.

Erak and Krans thank the Doctor, but decide to wait on Earth for the Nervans rather than transmat up to the station. As the two watch, Sarah, Harry and the Doctor vanish.




Story Notes

  • Working titles for this story included The Destructors.
  • Although the serial was the third to feature Baker, it was actually the second shot, hence the out-of-sequence production code.
  • This was only the second serial in the history of Doctor Who (the first being 1970's Spearhead from Space) to be shot entirely on location, in this case on Dartmoor. However, unlike Spearhead from Space and the location material for other serials, the production was mounted entirely on videotape using an Outside Broadcast unit, rather than on film as was more usual for the time.
  • During shooting, lead actor Tom Baker broke his collarbone. However, because part of his costume was a large scarf, he could conceal the neck brace he had to wear following the injury. For action scenes, he was doubled by regular stunt performer Terry Walsh, shot from several face-concealing angles.
  • This was the first two-part serial to be broadcast since 1965's The Rescue and the last until 1982's Black Orchid.
  • This was the first story to contain no interior scenes.
  • Glyn Jones, who played the astronaut Krans, wrote the First Doctor serial The Space Museum.
  • Kevin Lindsay makes his last Doctor Who appearances, playing Styre and the Sontaran Marshal. He died not long afterwards as a result of a long-standing heart condition.
  • All the Galsec astronauts have what sound like South African accents, implying a regional accent that these colonies have developed.


  • Part 1 - 11 million viewers
  • Part 2 - 10.5 million viewers


to be added

Filming Locations

  • The entire serial was filmed over seven days at Dartmoor National Park in Devon.
  • The major location was Hound Tor, Manaton, Dartmoor.

Discontinuity, Plot holes and Errors

  • If the Earth is uninhabited, why do the Sontarans need intelligence to invade it? They might think the Humans on the Nerva Beacon are ready to fight back at any moment. Also, they are invading the galaxy and there are more humans in it. The intelligence is regarding humans in general, who have a vast empire by this point throughout the galaxy.
  • During the fight when Styre's head is knocked sideways and when Styre touches his suit his head wobbles. The head cast is attached to the collar.
  • Why only send one Sontaran? Numbers are surely not unavailable in a cloned race? The earth is uninhabited so they don't need to send an army and since Styre can easily handle the number of humans he needs for his experiments with his robot, so there is really no point. Also the more they send the easier it is to notice them.
  • The face of the actor playing Styre has been painted black, this is clearly visible as their are large gaps between the inside of the head cast and the face of the actor.
  • In episode 2, Harry uses the word Sontaran despite not having heard it. He overheard Sarah call Styre a Sontaran (from his hiding place).
  • Harry is also looking for Sarah when he meets the torture victim, despite seeing her captured by the Sontaran at the beginning of the episode. Perhaps he was looking for where the Sontaran placed her or perhaps he though she had escaped.
  • Why did Sarah Jane think that Styre was Linx? Even though they were played by the same actor, they looked completely different. She might not have remembered Lynx that much and she was scared at the time; they look around about the same so Sarah was just confused.
  • Styre has five digits on each hand rather than Linx's three; this is the only story in which the Sontarans do not possess the usual three digits upon their hands. Styre has been specially engineered for research purposes and as such, has been given additional digits to make his hands more dexterous for manipulating delicate equipment. In PDA: The Infinity Doctors the issue of the varying number of digits on a Sontaran hand is explored.


  • This serial forms part of a continuous series of adventures for the TARDIS crew, beginning from the end of Robot and continuing through to Terror of the Zygons, although MA: A Device of Death takes place in a possible gap between Genesis of the Daleks and Revenge of the Cybermen, and PDA: Wolfsbane is set in another such gap between Revenge of the Cybermen and Terror of the Zygons.
  • The Sontarans are firmly established in this serial as a clone race, evidenced by Sarah thinking that Styre is Linx from DW: The Time Warrior. Although the same actor who played Lynx also plays Styre, the make-up and colouring are different (although the Marshal in this serial looks exactly like Styre).
  • The piece of metal which saves the Doctor's life was a synestic lock from Nerva's shuttle, which he removed during the previous story and put in his pocket.
  • Sarah Jane would reference the events of this story during her next encounter with the Sontarans in SJA: The Last Sontaran.

DVD, Video and other Releases

  • DVD release

Released as Doctor Who: The Sontaran Experiment (Special Value Edition) - one of the few occasions in which a two-episode story has been released by itself.



  • VHS Releases

This story was released in October 1991 as a double video, together with Genesis of the Daleks.

  • Boxset release

This story was released in the Bred for War DVD boxset on the 5th May Region 2 and 8th July Region 4 alongside all the classic series Sontaran stories. The DVD is the same as the one sold seperately.


Main article: Doctor Who and the Sontaran Experiment

External Links

  • BBC Episode Guide to The Sontaran Experiment
  • Doctor Who Reference Guide: Detailed Synopsis - The Sontaran Experiment
  • A Brief History of Time (Travel): The Sontaran Experiment
  • The Locations Guide to Doctor Who - The Sontaran Experiment
Season 12
Robot  • The Ark in Space  • The Sontaran Experiment  • Genesis of the Daleks  • Revenge of the Cybermen
Sontaran Television Stories
Doctor Who: The Time Warrior  • The Sontaran Experiment  • The Invasion of Time  • The Two Doctors  • The Sontaran Stratagem / The Poison Sky
The Sarah Jane Adventures: The Last Sontaran  • Enemy of the Bane
Minor Appearances: Logopolis  • The End of Time
Other: A Fix with Sontarans  • Shakedown: Return of the Sontarans

This article uses material from the "The Sontaran Experiment" article on the Dr Who wiki at Wikia and is licensed under the Creative Commons Attribution-Share Alike License.

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