Another adventure for everyone's favourite Time Lord. The TARDIS is forced to land on the planet Exxilon after suffering a sudden power loss. The Doctor (Jon Pertwee) and Sarah encounter a similarly stranded expedition from Earth, who are seeking a cure for the plague which is spreading rapidly across the galaxy. The Doctor believes that he can find a solution in the technologically advanced but long-abandoned city of the Exxilons, but becomes caught up in a power struggle between the humans and the latest arrivals to the planet: his old enemies, the Daleks.

Two classic Doctor Who adventures set on the planet of Peladon, starring Jon Pertwee as the Third Doctor, with Katy Manning as his companion in the first story and Elisabeth Sladen in the second. In the four-parter 'The Curse of Peladon' (1972), the Doctor (Pertwee) finally seems to have escaped his exile to Earth when he manages to transport Jo (Manning) in the Tardis to the planet Peladon. The pair are mistaken for Earth delegates at a conference to decide whether Peladon should join the Galactic Federation, and discover that someone is attempting to use the legendary royal beast of Aggador to trigger off a war. In the six-parter 'The Monster of Peladon' (1974), the Tardis arrives on the Planet of Peladon half a century after the Doctor's first visit. The planet has now become of great tactical importance because of its focal position between warring factions. The Doctor and Sarah (Elisabeth Sladen) have to act as peacekeepers between rival ambassadors and they must also find the truth behind 'the spirit'.

Jon Pertwee stars as the time travelling Doctor, who once more finds the planet under threat. Trying to avert a war which will bring Earth under the domination of the Daleks and their ferocious slaves (the Ogrons), the Doctor fights one of the biggest challenges he has faced so far.