The Doctor and Jo land on a spaceship in the far future as it is attacked by Ogrons, which the human crew see as Draconians. The Doctor and Jo are taken to Earth as spies.
Quest roles:
Peter Birrel(Draconian Prince), Ray Lonnen(Gardiner), James Culliford(Stewart), Louis Mahoney(Ponti), Roy Pattison(Draconian Space Pilot), Karol Hagar(Secretary), Barry Ashton(Kemp), Vera Fusek(President of Earth), Michael Hawkins(General Williams)