England is in civil war as the Royalists battle Oliver Cromwell’s Roundheads for control. This conflict distracts people from rational thought and allows unscrupulous men to gain power by exploiting village superstitions. One of these men is Matthew Hopkins (Vincent Price), who tours the land offering his services as a persecutor of witches. Aided by his sadistic accomplice John Stearne (Robert Russell), he travels from town to town and wrenches confessions from "witches" in order to line his pockets.