The Fifth Doctor, Tegan and Turlough arrive on Sea Base 4, a nuclear warhead station under the sea that has some very nasty neighbours.

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Main Cast: Peter Davison, Janet Fielding, Mark Strickson, Tom Adams, Ian McCulloch, Ingrid Pitt, Nigel Humphreys, Tara Ward, Martin Neil, Nitza Shaul

Director: Pennant Roberts

Writer: Johnny Byrne

Editor:

Cinematographer:

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