The Doctor and the Master are taken into the Primitive city, where the Master hopes to find the doomsday weapon, while Dent forces the colonists to leave the planet even though their ship is likely to explode.
Quest roles:
Nicholas Courtney(Brig. Lethbridge-Stewart), John Ringham(Ashe), Terry Walsh(Guard (uncredited)), Bernard Kay(Caldwell), Pat Gorman(Soldier), Roger Delgado(The Master), Helen Worth(Mary Ashe), Morris Perry(Dent), Tony Caunter(Jackson), Norman Atkyns(Rear Admiral), Roy Heymann(Gotal), Nicholas Pennell(Winton)