The Third Doctor becomes alarmed on seeing television coverage of an archaeological dig into an ancient barrow near the village of Devil's End. He hurries to the scene with Jo and finds The Master is posing as the local vicar, Mr Magister. The Master uses black magic to summon Azal, the last of a race known as the Dæmons, whose miniaturised spaceship is buried within the barrow. The Brigadier and his troops arrive to help them, but a heat barrier appears and cuts the village off from the outside world. Azal appears three times and on the last appearance decides whether to transfer his awesome powers to another, or to destroy the planet as a failed experiment. The Master hopes to be the recipient of the powers, but Azal instead offers them to the Doctor. The Doctor argues that the human race should be allowed to develop at its own pace. Azal decides to kill him, but when Jo offers to take his place the Dæmon self-destructs, unable to comprehend this act of self-sacrifice.