Casimiro, night watchman at a wax museum of horrors, is even more sleepy than his usual laziness makes him - because his boss, the Professor, is secretly draining blood from him while he dozes to use in experiments in raising the dead. These haven’t worked so far, and the bodies have been waxened and placed on display in the museum to cover his crimes. His big chance seems to come, however, when he learns that the mummified body of a modern man has been found in an Egyptian sarcophagus. The professor and his two henchmen steal the body and take it back to his lab - where the experiment flops again. Or it seems to. While the villains are out of the lab, and Casimiro sleeps on duty, a bolt of lightning gives the electrical boost which the Professor’s machinery has needed, and the body comes back to life. Then the clouds part, the full moon shines through, and the resurrected one becomes a were- wolf. When Casimiro sees it wandering the museum, no one will believe him, not even Paquita, his girlfriend. But the professor finds his subject alive and soon witnesses a transformation. Eventually, the creature escapes him and makes off into the night, terrorizing the city and ending up at Paquita’s apartment…