In the early 19th century, somewhere in the Confederation of the Rhine, a French soldier Andre is rescued by a mysterious Helene, who vanishes almost immediately. While searching for her, Andre uncovers secrets involving Baron von Leppe, his wife Liza, and the village witch Katrina. In the early 1960s, Roger Corman was riding a wave of success with American International Pictures, producing a series of Edgar Allan Poe adaptations like The Fall of the House of Usher (1960) and The Pit and the Pendulum (1961). However, Corman grew weary of the repetitive Poe series and sought new material while adhering to his notorious guerrilla-style, resourceful filmmaking, which led to the production of The Terror. As Corman and Jack Nicholson would later recall, the production was chaotic from start to finish. Vincent Price, who frequently starred in the Poe series, was unavailable due to scheduling conflicts, so Boris Karloff completed his scenes in just two days. Directors from Corman's gang, including Francis Ford Coppola, Monte Hellman, Jack Hill, and even Nicholson himself, took turns at the helm before Corman ultimately finished the film.