Armand Tesla, a former Romanian scientist who became a vampire because of his obsession with the occult, moves to London. He has a werewolf servant named Andréas (Matt Willis), and preys on one family until he is staked in 1918. When his grave is disturbed by Nazi bombs during World War II, gravediggers who have to rebury the overturned graves decide not to bury Armand with the stake, pulling it out. He then claws out of the ground. He seeks out Andréas, who now, after being turned back by Armand, has the power to change form at will, and sets out to take revenge on the family that had staked him. In the end, Andréas is shot trying to give Nikki (the doctor’s daughter) back to Armand. The vampire tells the lycanthrope, “I no longer had need of you.” After changing back, Andréas, who finds a cross buried in corner of the church Armand has made a home, pulls it out and starts forcing Armand up the stairs toward the sun. A bomb dropped from a passing German bomber lands in the church causing an explosion, destroying the building. Andréas finishes the job by dragging Armand into the sun, finishing Armand and releasing Nikki of Armand’s spell. Then Andréas is finally dead of his bullet wound, resting forever in peace.

This is one of only three films in which Bela Lugosi played a genuine vampire, the other two being Dracula and Abbott and Costello Meet Frankenstein. In Mark of the Vampire, Lugosi played a supposed vampire who turns out to be a fake. In Old Mother Riley Meets the Vampire, Lugosi played a mad scientist who has a delusion that he is a vampire.