The TARDIS lands on the idyllic jungle world of Deva Loka, which is being surveyed for possible Earth colonisation. Deva Loka is already home to a race of apparent savages, however: a mysterious people with strange powers which have mentally unbalanced the members of the expedition. To make matters worse, an ancient enemy of the natives known as the Mara is intent upon revenge, and latches onto Tegan's mind as its bridgehead to victory.
Peter Davison
Matthew Waterhouse
Sarah Sutton
Janet Fielding
Richard Todd
Nerys Hughes
Simon Rouse
Mary Morris
Sarah Prince
Adrian Mills
Lee Cornes
Jeff Stewart
Anna Wing
Roger Milner
Jonny Lee Miller