Patrick Troughton takes on the role of the Doctor for this TV serial in which his evil double plots to rule the world by triggering a series of volcanic eruptions. The action is set in near-future Australia, where the Doctor learns from an acquaintance named Giles Kent (Bill Kerr) that he is a dead ringer for Salamander (also Troughton), a high-profile figure who has devised a means of storing solar energy that enables him to unleash natural disasters at will. Through impersonating Salamander the Doctor discovers more about his plot, but, with his enemy also capable of impersonating him, the Doctor will face a stern test of his wits if he is to restore peace.