Taking drastic measures to escape a Tardis malfunction, the Doctor and Jamie arrive on a rocket, apparently deserted in space, and soon encounter its aggressive robot guard. When a blow to the head then renders the Doctor unconscious, Jamie's only hope of rescue lies in contacting the Wheel space station which is orbiting nearby. In fact the rocket has other occupants, who are sending out mysterious egg-like spheres to penetrate the Wheel's outer surface.
What dangerous cargo do the spheres bring to the human crew of the Wheel, and what is the intention of those who are sending them? It's not long before the Doctor and Jamie realise that their old adversaries, the Cybermen, are seeking to invade first the Wheel and then Earth itself...
Patrick Troughton's Doctor once more confronts the Cybermen in this exclusive recording of a 'lost' television adventure, with linking narration by Wendy Padbury, who played the Doctor's companion Zoe.