The TARDIS arrives on the unnamed planet of the Gonds, who are ruled and taught in a form of self-perpetuating slavery by the alien Krotons — crystalline beings whose ship, the Dynatrope, crash-landed there thousands of years earlier after being damaged in a space battle. The Krotons are in suspended animation, in a crystalline slurry form, awaiting a time when they can be reconstituted by absorption of mental energy. Periodically, the two most brilliant Gond students are received into the Dynatrope, nominally to become "companions of the Krotons", but in truth to have their mental energy drained, after which they are killed.
as The Doctor
as Jamie McCrimmon
as Zoe Heriot
as Selris
as Beta
as Thara
as Eelek
as Abu
as Vana
as Axus
as Custodian
as Student
as Kroton Voice
as Kroton Voice
as Kroton
as Kroton
