Following the Doctor's regeneration into a new, younger body, the TARDIS lands at an Earth colony on the planet Vulcan in the far future. Mistaken for an official Earth Examiner, the Doctor discovers that a scientist called Lesterson is attempting to reactivate two inanimate, subservient Daleks found in a crashed space rocket. The colonists refuse to heed the Doctor's dire warnings that the Daleks are dangerous. Once reactivated, the Daleks secretly begin to reproduce themselves in a bid to seize control of the Earth colony.