Doctor Who and the Silurians (also known simply as The Silurians) is the second serial of the seventh season in the British science fiction television series Doctor Who. It was first broadcast in seven weekly parts on BBC1 from 31 January to 14 March 1970. The serial is set in an English moorland, the cave system below it, and London. In the serial, the alien time traveller the Third Doctor (Jon Pertwee) attempts to broker peace between humanity and the Silurians, an intelligent bipedal race of reptilians that ruled Earth before humans. This effort becomes undone by a xenophobic usurper Silurian, along with gung-ho human soldiers. The story is the first appearance of the Silurians, for whom the Silurian hypothesis in science is named. Plot A nuclear powered cyclotron facility in some caves under a moorland is experiencing mysterious power drains and mental breakdowns amongst staff. The Third Doctor and Liz Shaw meet Brigadier Lethbridge-Stewart there to investigate. A worker who was potholing in the caves is found dead with giant claw marks on his body, and his companion has been traumatised. Lawrence, the Director, resents UNIT's presence and feels that it will interfere with the working of the plant. Major Baker, the security chief, believes there is a saboteur in the centre, and the Doctor discovers that the logs of the nuclear reactor's operation have been tampered with. When the Doctor makes his way into the caves, he is attacked by a dinosaur-like creature before it is called off by a strange whistling sound. The Doctor analyses blood from a man-sized creature Major Baker shot at and finds similarities to "larger reptiles". In the meantime, the creature goes to the moorland on the surface and stumbles into a barn to hide. Quinn goes into the caves to a hidden base, where he demands the knowledge he was promised. He is told that he must first help the wounded creature and is given a signal device, which emits the sound heard earlier. The creature attacks a farmer and his wife when they discover it in the barn. The farmer dies of a heart attack after being frightened by it, but the wife survives and identifies her attacker. While investigating the barn, Liz is knocked unconscious by the creature, and it flees. The Brigadier and the Doctor follow the creature's tracks and find they end in tyre marks. Breaking into Quinn's