When the TARDIS materializes in medieval Worcester, the Doctor finds the city seemingly deserted. He soon sees that the local population lives in constant terror, afraid to leave their homes after dark for fear of losing their lives at the hands of the legendary Devil Hunter. People have been missing for months, and the sheriff has declared a strict curfew, his militia firmly maintaining control. over the superstitious people, closing the city from outsiders. Is it the fear of attack from beyond the city walls that drives them, or is the threat lurking closer to home? Or does the sheriff have something to hide? After a terrifying encounter with a deadly Krillitan, the Doctor realizes the town has good reason to be afraid.