After a drunk wanders into and disrupts his secret lab, Dr. Frankenstein (Peter Cushing) decides he must find a new place to set up shop. Conveniently, he finds an innocent young girl (Veronica Carlson) who happens to have a boyfriend (Simon Ward) employed by the local hospital. Seeing his opportunity, Dr. Frankenstein kidnaps the couple and forces them to take part in a dangerous brain-swapping experiment.