A warlock flees from the 17th to the 20th century, with a witch-hunter in hot pursuit. A Warlock (Julian Sands) is taken captive in Boston, Massachusetts in 1691 by a witch-hunter Giles Redferne (Richard Grant). He is sentenced to death for his activities, including the bewitching of Redferne's bride-to-be, but before the execution a demon appears and propels the Warlock forward in time to 20th century Los Angeles, California. Redferne follows through the portal.
The Warlock attempts to assemble The Grand Grimoire, a Satanic book that will reveal the "true" name of God. Redferne and the Warlock then embark on a cat-and-mouse chase with the Grand Grimoire, and Kassandra (Lori Singer), a waitress who encounters Giles while he's attempting to find Warlock.