The Sontaran Experiment is the third serial of the 12th season of the British science fiction television series Doctor Who, which was originally broadcast on BBC1 on 22 February and 1 March 1975. The serial is set on Earth more than 10,000 years in the future, immediately after the events of The Ark in Space. In the serial, the Sontaran Field Major Styre (Kevin Lindsay) performs experiments on humans he trapped there as part of the Sontarans' invasion stratagem. Plot Following on from The Ark in Space, the Fourth Doctor, Sarah Jane Smith, and Harry Sullivan teleport down from the Nerva space station to Earth, ostensibly uninhabited. However, the system is not functioning well, and the Doctor begins repairing it. The other two explore the surrounding area, but Harry falls down a crevasse and Sarah goes to seek the Doctor's help. He is nowhere in sight. Roth, an astronaut, finds Sarah. He is obviously distressed, and explains that he has been tortured by an alien that lives in the rocks, together with its patrolling robot. He takes Sarah towards the astronauts' campsite, but refuses to approach it, suspecting the astronaut Vural of collusion with the alien. Three of the astronauts have captured the Doctor. They believe Nerva to be a legend, and tell him in turn that they had picked up a distress signal from Earth. They came to investigate, but their ship was vapourised when they emerged, leaving nine of them stranded. Then they began to vanish one by one. They blame the Doctor for this. Roth appears and the astronauts chase him, while Sarah frees the Doctor. Roth loses the others and meets up with Sarah and the Doctor. The Doctor also falls down a crevasse, and the robot returns, capturing Roth and Sarah and bringing them to the alien's spacecraft. The alien is Field Major Styre of the Sontaran G3 Military Assessment Survey, who has been experimenting on, and killing, the astronauts. Roth tries to escape but is shot dead by Styre. Styre reports back to his Marshal via a video link. The Marshal is impatient for the intelligence report (without which an invasion of Earth cannot take place), but Styre admits that he has been delayed in his experiments. Styre subjects Sarah to a series of terrifying hallucinations. The Doctor, free from the hole, has reached her and rips off a hallucinogenic device from her forehead,