The Haunted House of Horror is a British horror film starring Frankie Avalon and Jill Haworth. The film's tagline read 'Behind it's forbidden doors an evil secret hides!' A group of twenty-something friends are attending a dull party when they decide to get some excitement by visiting an old, supposedly haunted mansion where one of them played as a child. They begin exploring the mansion, even holding a séance before separating one by one using candlelight to light their way. Gary (Mark Wynter) is brutally knifed and his lifeless body discovered by the panic-stricken Dorothy (Carol Dilworth) and the others. Some of the party-goers have a criminal record, so Chris (Frankie Avalon) convinces the group to leave Gary's dead body far from the mansion and pretend that Gary simply left with no one knowing where he went. Weeks go by and the survivors are possessed by guilt when Gary is reported missing and the police question the surviving party-goers. Kellet (George Sewell), Sylvia's ex-boyfriend, questions Sylvia (Gina Warwick) learning that she may have lost a lighter that could link her to the mansion. Kellet returns to the mansion, but is also killed. Dorothy (Carol Dilworth) calls the others together to try to get someone to confess to the murders, but Chris (Frankie Avalon) convinces them to return to the mansion to discover who among them is the killer before they all succumb to a gruesome death. Meanwhile, Sylvia is visited by the police again, and she discloses the location of the mansion after learning of Kellet's disappearance. At the mansion, Richard (Julian Barnes) confesses that as a child he was locked in a basement for three days, and tells the others he has a paralyzing fear of the dark. The horror does not end here, and the tagline is correct that 'Behind it's forbidden doors an evil secret hides!' 88 minutes - 1969 - Color - 16:9 (Widescreen).