An energy drain traps the Third Doctor and Sarah Jane Smith on the planet Exxilon with its hostile natives, causing the travellers to make an uneasy alliance with a Marine Space Corps expedition and a squadron of Daleks. The key to escape for all of them lies at the heart of a powerful and mysterious lost city, but only after a series of deadly traps.
Jon Pertwee
as The Doctor
Elisabeth Sladen
as Sarah Jane Smith
Duncan Lamont
as Dan Galloway
John Abineri
as Richard Railton
Joy Harrison
as Jill Tarrant
Julian Fox
as Peter Hamilton
Neil Seiler
as Commander Stewart
Arnold Yarrow
as Bellal
Roy Heymann
as Gotal
Mostyn Evans
as High Priest
Michael Wisher
as Dalek Voices
John Scott Martin
as Dalek
