The legendary scientist's son is tempted to resume his father's horrible experiments.

The memory of horror provoked by the man-made monster still endures when Baron von Frankenstein, accompanied by his wife Elsa and young son, arrives from America at his ancestral home in a small European mountain village to claim his late father's estate. Soon after, the baron meets his father's demented assistant, Ygor, who has robbed death by coming back to life after being cut down from the hangman's scaffold. Ygor tells the baron that his father's monster lives, and leads the young scientist through a secret passage to an outside mountain laboratory where the monster slumbers deep in a coma. Determined to prove that his father's experiments were meant to aid and not injure humanity, the baron restores the monster to life. Before he can transform the monster's brute nature, however, Ygor uses the creature as an instrument of revenge, ordering it to kill the jurors who had sentenced him to hang. The renewed terror in the village holds special significance to police inspector Krogh, who, as a boy, lost his arm in an attack by the monster. Krogh enters into a battle of wits with the baron, who is determined to conceal the monster for further experiments. However, when Ygor and the monster threaten the life of his young son, the baron finally realizes the evil that the creature embodies and, after shooting Ygor, obliterates the monster in a seething sulphur spring, thus ending the threat of evil forever.