The Doctor's TARDIS materialises in the village of Lannet in Lancashire. An annoyed Doctor, who has apparently been transported here against his will. He discovers the village silent, its inhabitants all living in fear except for a barmaid, Alison Cheney. The alien Shalka have taken up residence beneath Lannet in preparation for a wider invasion. Despite his initial reluctance, the Doctor finds himself having to save the world again, aided by Alison and an enemy who has become an ally.