After the killing of his father (Count Dracula, the King of the Netherworld), by a mysterious assassin, Count Downe (Harry Nilsson) is summoned from his travels abroad by family advisor Merlin (Ringo Starr) in order to prepare him to take over the throne. Baron Frankenstein (Freddie Jones) is also on hand to help in any way he can. Problem is, Downe wants no part of this responsibility, and instead wishes to become human and mortal − especially after meeting a girl named Amber (Suzanna Leigh), with whom he falls in love. He approaches old family nemesis Dr Van Helsing (Dennis Price), who agrees to enable the Count’s transformation, much to the dismay of the residents of the Netherworld.
Despite the best efforts of a host of monsters, as well as one traitorous figure who is dealt with by the trusted Merlin, Van Helsing performs the operation and removes Downe’s fangs. He then informs the Count that he can now live out his days in the sunlight, with Amber at his side.
Keith Moon of The Who and John Bonham of Led Zeppelin both appear in the film, alternating as drummer in Count Downe’s band. Other band members include Klaus Voormann (another old friend of Starr’s), Peter Frampton, an uncredited Leon Russell, and the regular Rolling Stones horn section of Bobby Keys and Jim Price.