Trying to get Tegan back to Heathrow in 1981, the Doctor brings the TARDIS to the right place, but over 300 years early – in 1666. They are not the only visitors as Death stalks the local woods, complete with cloak, scythe and a skull-like face. In fact, ‘Death’ is an android brought by a group of alien Terileptils whose spaceship has crashed. Criminals and fugitives from their own race, they now plan to take over Earth. With Adric and Tegan captured, the Doctor and Nyssa try to deal with the deadly android, and a group of local villagers under the control of the Terileptils. But even if they succeed, can they prevent the Terileptils from unleashing an even more deadly from of the Black Death?