The Haunted House of Horror

A group of twenty-something friends gather for kicks at an old supposedly haunted mansion where one of their number used to play as a child. Among the group is American ringleader Chris, his bored partygirl girlfriend Sheila, promiscuous Sylvia who has her eye on handsome two-timing Gary, and his "good girl" date Dorothy. While all the partiers are alone, Gary is brutally knifed; his body is discovered by the panic-stricken Dorothy.