Classic British sci-fi adventure starring Jon Pertwee. When the Doctor engineers his escape from BOSS, he discovers that Cliff has been infected by a giant maggot.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor tries to destroy the maggots and cure Cliff, but the real danger is BOSS, who is set to take over the world's computers.

Classic British sci-fi adventure starring Jon Pertwee. The Brigadier asks the Doctor to search for a number of missing scientists who, he discovers, have been sent back in time.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor traces the scientists to Irongron's castle where they have been put to work repairing a spaceship and creating weapons.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor escapes the confines of the castle and must convince Sir Edward to trust him before Irongron launches an attack.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor attempts to return the scientists to their own time, while Linx tries to use his spaceship - with destructive results.

Classic British sci-fi adventure starring Jon Pertwee. The TARDIS is diverted to the barren planet Exxilon where the Doctor discovers the Daleks are searching for a cure to a space plague.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor forms an unlikely alliance with the Daleks to mine the parrinium only to come under attack from the Exxilons.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor and Sarah meet with Bellal, who helps them evade the Daleks and explains the origin of the city.

Classic British sci-fi adventure starring Jon Pertwee. The Doctor and Bellal penetrate the city's defences while Sarah and Jill try to stop the Daleks from escaping with the parrinium.