Parts: 4
Writer: Peter Grimwade
Airdates: 23 February 1984 - 2 March 1984
Production Code: 6Q

Doctor: fifth
Companions: Turlough, Kamelion, Peri

Megalomaniac of the Week: the Master

Story: Strange things are happening onboard the TARDIS - Kamelion, hooked up to the TARDIS' databanks, is suffering great pain; Turlough intercepts, and tries to hide, a Trion signal; and the ship's co-ordinates mysteriously change. The new co-ordinates send the TARDIS to the island of Lanzarote, from whence the signal seems to originate. While the Doctor tries to determine its location, Turlough rescues an American girl, Peri Brown, from drowning - and among her possessions is a strange metal artefact bearing a symbol that exactly matches one on Turlough's left arm.

The Doctor traces the artefact back to the volcanic planet of Sarn, an old Trion colony, where the locals are agonizing over the existence of their god, Logar. The arrival of the TARDIS is seen by some as their salvation - but not by all. Meanwhile, in the TARDIS, Peri's thoughts have caused Kamelion to assume the shape of her stepfather Howard - but once the Doctor and Turlough leave the ship, Kamelion's features swirl and change...into those of the Master.

Peri barely manages to escape from the Master, but her quest to find the Doctor leads her into the inhospitable landscape of Sarn - and the Master is stalking her with intent to kill. And when the Doctor and Turlough are revealed as mere humans and not the messengers of Logar, the god's followers seize the moment to order all unbelievers burned in Logar's fire. As the volcano beneath everyone's feet threatens to erupt, Turlough makes an astonishing discovery about his past...and the Master has a plan to be reborn.