Jo (Katy Manning) and the Doctor (Jon Pertwee) have been sent on a mission by the Time Lords to deliver a package to a recipient on the planet Solos. Arriving on a nearby space station, the Doctor becomes involved in the planet's struggle to gain its independence from Earth's colonial powers. But the current colonial leader, a man known only as the Marshal, is not keen to give up control, and is planning to bomb the inhabitants out of existence.

Hammer Studios' imaginative twist on the classic Robert Louis Stevenson novel. In Victorian London, Dr Jekyll (Ralph Bates) experiments to discover an elixir of life. After mixing up the hormones he has taken from dead bodies, Jekyll is transformed into a beautiful but murderous female (Martine Beswick).