As he sits on death row, Baron Victor Frankenstein (Peter Cushing) confesses how he and his mentor (Robert Urquhart) performed grotesque scientific experiments, culminating in the creation of a creature (Christopher Lee) pieced together from human body parts and reanimated. The Baron's invention is a murderous monster that will do his bidding -- until the day it turns against its master and threatens to kill his fiancée (Hazel Court).