The "Doctor" (Tom Baker) is diverted from his galactic ambling by a messenger from the Time Lords who demands that he go to the planet "Skaro" where he must thwart the aspirations of a megalomanic scientist. Reluctantly, he, "Sarah Jane" (Elisabeth Sladen) and "Harry" (Ian Marter) set off and soon find themselves in a militaristic society ruled by "Davros" (Michael Wisher). He's paralysed below the waist, has only one hand, one eye and moves around in a motorised chair supported by his menacing aide "Nyder" (Peter Miles) - and he has only one aim. To develop his Mk 3 travel machine into an all ...