When the Master steals the Time Lords' secret file on the Doomsday Weapon, they grant the Doctor a temporary reprieve from his exile on Earth to deal with the crisis. He and Jo arrive on the planet Uxarieus and become enmeshed in a struggle between an agrarian colony and a powerful mining corporation.
Jon Pertwee
as The Doctor
Katy Manning
as Jo Grant
Nicholas Courtney
as Brigadier Lethbridge-Stewart
Roger Delgado
as The Master
Nicholas Pennell
as Winton
John Ringham
as Ashe
David Webb
as Leeson
Sheila Grant
as Jane Leeson
Roy Skelton
as Norton
Helen Worth
as Mary Ashe
John Line
as Martin
Mitzi McKenzie
as Mrs. Martin
