Written by David Whitaker
Directed by Barry Letts
The travelers arrive in Australia in the near future and learn from a man named Giles Kent that the Doctor is the physical double of Salamander, a scientist and politician who has discovered a means of storing and distributing solar energy and thus ending starvation in a world ravaged by natural disasters.
Most people see Salamander as a hero, but Kent and others believe him to be establishing himself as a dictator. The Doctor uncovers the truth by impersonating Salamander and gaining access to his research station. Salamander and Kent were originally working together. Almost five years ago, they convinced a group of people undergoing an endurance test in a bunker beneath the station that a war had broken out on the surface.
It is these people, led by a man named Swann, who, deceived into thinking that they are striking back against an evil enemy, have been engineering the so-called natural disasters. Kent, now exposed as a traitor, blows up the station. Salamander meanwhile tries to escape in the TARDIS by impersonating the Doctor. He neglects to close the doors before dematerialization, however, and is sucked out into the vortex.