Subtly spooky Hammer Films horror, scripted by Richard Matheson from Dennis Wheatley's novel, stars Christopher Lee as the Duc de Richleau, a French nobleman living in England. Trying to save an old friend's son who's scheduled to lose his soul at the hands of a Satan-worshipping cult, Richleau is forced to perform deadly rituals that draw him into conflict with the Devil himself. With Charles Gray, Leon Greene, Niké Arrighi, Patrick Mower.