The Doctor and Romana arrive on the marsh moon of Delta Magna in search of the next segment of the Key to Time. They are caught in the conflict between the native Swampies and the crew of a chemical refinery. The presence of a gun runner complicates matters; to make things worse, the Swampies intend to awaken Kroll, the giant god that lives beneath the swamps.

Tom Baker
as The Doctor

Mary Tamm
as Romana

Neil McCarthy
as Thawn

John Abineri
as Ranquin

Philip Madoc
as Fenner

Glyn Owen
as Rohm-Dutt

Carl Rigg
as Varlik

Frank Jarvis
as Skart

John Leeson
as Dugeen

Grahame Mallard
as Harg
CinemaSerf
You might get the impression from watching this that the budgets were already a bit stretched for this season, so they just resorted to some green body paint to create a race of rudimentary "Swampies" who are rebelling against some human interlopers who have plonked a drilling rig off their coast. T...