St. Mariah's Hospital for the criminally insane achieves a new level in sadistic horror when a group of vampires that have been used as human guinea pigs begin to put the bite on Christmas party guests gathered for a grand (Guignol) ball. At the same time, an undercover reporter tries to rescue her incarcerated brother before he becomes the head vamp's latest tidbit.

Deformed since birth, a bitter man known only as The Phantom lives in the sewers underneath the Paris Opera House. He falls in love with the obscure chorus singer Christine, and privately tutors her while terrorizing the rest of the crew.