Having just saved his home planet from a fate worse than death, the now solitary "Doctor" lands his TARDIS on a world where he has clearly been before! His arrival is quite timely as "Leela" (Louise Jameson) is about to be banished from her tribe. They meet and stick together as it becomes increasingly obvious to the forgetful "Doctor" (Tom Baker) that the warring "Sevateem" tribe are out for his blood. Why? Well as we progress we discover that there are two tribes on the planet. One are pretty primitive, the others much more sophisticated and the "Doctor" starts to figure that the latter are ...