London provides the setting for this story about an occult novelist (Richard Widmark) who is enlisted to safeguard a young nun (Nastassja Kinski) from a cult of satanists led by a towering figure with apparent supernatural abilities (Christopher Lee). The cult intends to use her in some sort of sinister ritual. Honor Blackman appears in a minor role. "To the Devil a Daughter," released in 1976, is a loose adaptati…