Curse of the Crimson Altar

Curse of the Crimson Altar is a 1968 British horror film directed by Vernon Sewell and starring Christopher Lee, Boris Karloff, Barbara Steele and Mark Eden. The film was produced by Louis M. Heyward for Tigon British Film Productions. The film was edited and released as The Crimson Cult in the United States. The screenplay, by Doctor Who writers Mervyn Haisman and Henry Lincoln, was based (uncredited) on the short story "The Dreams in the Witch House" by H. P. Lovecraft. This film also featured one of the final film appearances of horror superstar Karloff.

Plot
Antiques dealer Robert Manning (Eden) searches for his brother, who was last known to have visited the remote house of Craxted Lodge at Greymarsh, their family's ancestral town. Arriving at night, he finds a party is in progress, and he is invited to stay by Eve (Wetherell), the niece of the owner of the house. His sleep is restless and strange dreams of ritual sacrifice disturb him. Enquiring about his brother, he is assured by the house owner, Morley (Lee), that the man is not there. Manning's suspicions are aroused by nightmarish hallucinations. Occult expert Professor Marsh (Karloff) informs Manning about a witchcraft cult led by Morley's ancestor, Lavinia (Steele). The cult is discovered to still be active. Craxted Lodge is burned to the ground, and the head of the cult is consumed in the flames.