AllMovie

In the second episode of the four-part story "The Ark in Space," the Doctor (Tom Baker), Sarah (Elisabeth Sladen), and Harry (Ian Marter) endeavor to protect the last inhabitants of planet earth, who are being kept in a cryogenically frozen state on the deserted space station Nerva Beacon. Successfully shielding the station from a dangerous surge of solar activity, the time travellers discover that an even greater danger lurks within the walls of the Nerva Beacon itself -- a danger manifested in the body of a long-dead member of the insectasoid Wirrrn species. Written by Robert Holmes, "The Ark in Space, Episode 2" originally aired on February 1, 1975.