The Fifth Doctor, Tegan and Turlough arrive on Sea Base 4, a nuclear warhead station under the sea that has some very nasty neighbours.
as The Doctor
as Tegan Jovanka
as Vislor Turlough
as Vorshak
as Nilson
as Solow
as Bulic
as Preston
as Maddox
as Karina
as Paroli
as Icthar
as Scibus
as Tarpok
as Sauvix
as Seabase Crewmember