Avsnitt 20

William Grimes, the leader of an exploration team from an Arctic research facility, goes crazy while exploring an ice cave and kills two colleagues before dying himself. Psychologist Jack Burrell is sent up to counsel the staff at the facility. Among his patients is the head of the facility, Robby Archer, a friend from his boyhood. It is not a happy reunion because of a traumatic childhood incident they shared but now they must work together . Grimes has infected the facility with polar mites, a strange ant-like species who take up residence in the warm tissue of the human body and create sort of psychosis.