After an encounter with a hostile robot called a Chumblie, the Doctor and his companions are rescued by a group of female Drahvins.

With the knowledge that the planet will be destroyed in two days, the Drahvins instruct the Doctor to help them steal the Rills' ship.

The Doctor and Vicki encounter the Rills and learn the situation is more complex than they thought while Steven finds the Drahvins' hospitality ever more perilous.

The Doctor and Vicki enlist the aid of the Chumblies to rescue Steven from the Drahvins and then find a way off the planet before its destruction.