The film was first released theatrically in Germany (as Dracula jagt [hunts] Frankenstein) on February 24, 1970, and in Spain (as The Monsters of Terror) on August 28, 1971.

[citation needed] Aliens, occupying the bodies of deceased Earth scientists, revive a vampire, a werewolf, a female mummy, and Frankenstein's monster with a plan to use them to take over the human race by using their own primitive superstitions against them.

[citation needed] The werewolf Waldemar Daninsky saves the world by destroying the other three monsters in hand-to-hand combat and ultimately blowing up the aliens' underground base; however, he is shot to death in the film's finale by a woman who loves him enough to end his torment.

[citation needed] Lead actor Paul Naschy also wrote the screenplay at the request of producer Prades, who was impressed by the box office success of Naschy's La Marca del Hombre Lobo that year and wanted to film a sequel.

Naschy claimed that Hollywood actor Robert Taylor volunteered to play the lead alien in the film, but the producer hired Michael Rennie instead.

)[8] Naschy was told the film would have a lavish budget, which inspired him to let his imagination run wild while writing the screenplay.

Whole segments of the script involving flying saucers and the Golem were never carried out as the result of sorely lacking funds.

[citation needed] The film is available today on a DVD from Reel Vault under the title Assignment Terror, as well as on a German Blu-Ray under the title Assignment Terror (Dracula Jagt Frankenstein)[9] The film was broadcast on Tele 5 as part of the programme format SchleFaZ in season 2.