The movie is sometimes linked to Corman's contemporary series of films based on the works of Edgar Allan Poe, but The Terror is not based on any text by Poe.
Set in 1806, the film tells the story of a lost French soldier in the Confederation of the Rhine named Andre Duvalier (Jack Nicholson) who is saved by a strange young woman named Helene (Sandra Knight). She looks like Ilsa, the wife of the baron (played by Boris Karloff), who died twenty years before.
Investigating who the woman really is, Andre stumbles upon a hidden secret of the Baron: After he found Ilsa sleeping with another man named Eric, the Baron killed his wife while his servant killed Eric, or so he explains.
All the while, the phantom of Ilsa remained under the control of a peasant witch (Dorothy Neumann), who has commanded the ghost to torment the Baron for the previous two years. Over the course of the film, Ilsa's ghost beseeches the Baron to kill himself, so they could be together. After much hesitation, the Baron decides to do so, perhaps to atone for his crimes.
During the climactic scenes, Andre, as well as the Baron's butler Stefan (Dick Miller), try to stop him, eventually forcing the witch into compliance. Here it is revealed that the witch Katrina is in fact the mother of Eric, who she believes was killed by the Baron twenty years before, and that is why she has tried to make him commit suicide and damn his soul to hell. In a stunning revelation, Stefan reveals that Eric never died, that it was the Baron who was killed. Eric then took the Baron's place, living his life until he deluded himself into thinking he was the Baron.
Katrina, realizing her folly only too late, goes with the two men to stop Eric from flooding the castle crypt and killing himself. However, Katrina's pact with the devil makes her unable to go into the consecrated ground of the mausoleum and ends up being struck by lightning and burning to death to the ground as she tries to escape.
In the climax of the film, Ilsa's ghost attempts to kill Eric while the crypt floods, and Stefan joins the struggle. However, by the time Andre gains access to the crypt, it is already flooding and crumbling, and he is able to carry only Helene's body away. the film ends as the two share a touching moment together outside before Helene begins to rapidly dissolve into a rotting corpse.Boris Karloff as the Baron von Leppe/Eric
Jack Nicholson as Andre Duvalier
Dick Miller as Stefan
Sandra Knight as Helene/Ilsa
Dorothy Neumann as Katrina the Witch
Jonathan Haze as Gustaf
The film was released on a double bill with Dementia 13.
The Los Angeles Times thought it 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".
Today, the film is in the public domain since there is no copyright notice in the credits for the film.
In the early 1990s, actor Dick Miller, who plays Karloff's major domo, was hired to shoot new scenes to use as a framing sequence for an overseas version of The Terror. Under this scheme, the main action of the film is presented in flashback. This was done for Corman to establish some sort of copyright in the movie. Dick Miller says the payment for these scenes was the most he had ever received from Corman.
In May 1966, Corman told Karloff he would not be getting his deferred $15,000 since the film never made $150,000. However, he said he would pay the money if Karloff worked on a new undetermined future project for Corman. This turned out to be the Peter Bogdanovich movie Targets (1968), which extensively used clips from The Terror. Karloff was paid his deferred fee once he agreed to be in Targets.
In 2010, the film was featured in the second episode of the revived, syndicated TV series, Elvira's Movie Macabre. The climax scene was shown in the 2013 film Avenged.
The Terror, restored from original 35mm elements, was released April 26, 2011 from Film Chest and HD Cinema Classics. It is presented in widescreen with an aspect ratio of 16 x 9 and 5.1 surround sound mix. Enclosed is a collectible postcard reproduction of the original movie poster and special features include Spanish subtitles, before-and-after film restoration demo and trailer.