The Fifth Doctor, Tegan and Turlough arrive on Sea Base 4, a nuclear warhead station under the sea that has some very nasty neighbours.
Peter Davison
as The Doctor
Janet Fielding
as Tegan Jovanka
Mark Strickson
as Vislor Turlough
Tom Adams
as Vorshak
Ian McCulloch
as Nilson
Ingrid Pitt
as Solow
Nigel Humphreys
as Bulic
Tara Ward
as Preston
Martin Neil
as Maddox
ניצה שאול
as Karina
James Coombes
as Paroli
Norman Comer
as Icthar
