Paul Naschy plays a hunchback with below average intelligence who works at the morgue. He is in love with a sickly girl who happens to be the only person who is kind to him. Each day he brings her flowers until the day she dies.

The legendary Loreley has been living for centuries in a grotto beneath the river Rhein in Germany. Every night when the moon is full, she turns into a reptile-like creature craving for human blood. When one girl after another of a nearby boarding school is killed by her, a hunter named Sirgurd is engaged to kill the monster.