The film stars Boris Karloff and Jack Nicholson, the latter of whom portrays a French officer who is seduced by a woman who is also a shapeshifting devil.

The movie has become famous because of the circumstances of its production, including that all of Boris Karloff's scenes were shot in two days, the long time it took to complete, the number of people who worked on it that became famous, and the part the film played in the financing and production of Targets (1968), directed by Peter Bogdanovich and starring Karloff.

[2] Corman wrote in his memoirs that The Terror "began as a challenge: to shoot most of a gothic film in two days using left-over sets from The Raven.

Katrina reveals herself to be the mother of a man named Eric, whom she believes was killed by the Baron 20 years earlier.

Realizing her error too late, Katrina goes with André and Stefan to stop Eric from flooding the castle crypt.

Katrina's pact with the devil, however, makes her unable to walk on consecrated ground and she ends up burning to death after being struck by lightning.

At the von Leppe castle, Eric floods the crypt as Ilsa's ghost attempts to kill him and Stefan struggles to stop her.

Roger Corman had enjoyed considerable success in the early 1960s producing and directing films based on the stories of Edgar Allan Poe for AIP: The House of Usher, The Pit and the Pendulum, The Premature Burial, Tales of Terror and The Raven, as well as the Poe-influenced Tower of London.

Corman wrote in his memoirs that he was inspired to make The Terror because "I was getting so familiar with the standard elements of Poe's material – or at least our adaptations – that I tried to out-Poe himself and create a Gothic tale from scratch.

The weekend before filming was scheduled to end, Corman intended to play tennis with a friend but the game was rained out.

[3] Corman contacted Leo Gordon, an actor and writer who had written several films for the director, including The Cry Baby Killer and The Wasp Woman, and asked him if he had a script with a castle in it.

According to Dick Miller's account of making The Terror, Corman "called Chuck Griffith and said, "Write me a bunch of scenes for Boris Karloff and this castle."

Corman hired Jack Nicholson and Dick Miller, with whom he had worked several times previously, to play the other male roles.

"[9] Corman had recently hired Francis Ford Coppola to work as his assistant on Battle Beyond the Sun and The Haunted Palace, and assigned him to direct the rest of The Terror.

Coppola went to Big Sur for what was meant to be three days to shoot additional footage using a crew of film students from UCLA.

Nicholson says this involved "the stuff along the beach and the rocks with Jackie Haze, the horse, Helene, the young woman, and the witches raven.

"[13] The crew included Jack Hill, who had done a number of jobs for Corman, and Gary Kurtz, who met Coppola during the making of the movie, starting a long collaboration between the men.

"[10] Nicholson says that he almost drowned shooting a scene in the ocean at Big Sur – he was knocked over by a wave and his uniform almost dragged him down.

[13] Corman says that once there Coppola decided to "change and improve the script" and came back with footage that "didn't exactly mesh with what I had shot.

"[11] Corman still needed more footage for the flooding sequence, but then Coppola accepted a job at Seven Arts and was no longer available to do the required work.

Coppola recommended a friend from UCLA, Dennis Jakob, who Corman hired to shoot shots of water at Hoover Dam.

[16] Corman felt The Terror still required more work, so he hired Monte Hellman to shoot exteriors at the cliffs of Palos Verdes with Nicholson and Miller and scenes at Santa Barbara.

It required a whole change in story... That's when I got the screen credit for working on the script because eventually quite a bit of what I wrote was in the final picture and a lot of what Francis did was thrown out.

[18] Corman says that when he cut together Karloff's footage, he realized that "it didn't make sense" so he filmed a scene between Dick Miller and Jack Nicholson (in close-up because the sets had been taken down) and got them to explain the plot.

[13] Corman says he shot this scene between Nicholson and Miller on the last day of The Haunted Palace using the crew from that film.

[23] The Los Angeles Times thought The Terror was "spooky" with a "slow, lazy plot" and "Excellent photography and settings... it moves like a stately pavan but the authors exhibit some of that old Edgar Allan Poe touch for haunted happenings".

[26] In 1990, actor Dick Miller, who plays Karloff's majordomo, was hired to shoot new scenes to use as a framing sequence for an overseas version of The Terror.

[6] The 1990 version of the film ran 91 minutes and was released on DVD in the UK as The Haunting (copyright at the end is to Concorde and New Horizons, companies owned by Corman).

It featured scenes starring Wayne Grace as the son of the Karloff character (who irrelevantly summons forth a flying ghost in a satanic ritual) and Rick Dean as his dungeon torturer.

Enclosed is a collectible postcard reproduction of the original movie poster and the special features include Spanish subtitles, a before-and-after film restoration demo and a trailer.