Corman offered Coppola the chance to direct a low-budget horror film in Ireland with funds left over from Corman's recently completed The Young Racers, on which Coppola had worked as a sound technician. The producer wanted a cheap Psycho copy—complete with gothic atmosphere and brutal killings—and Coppola quickly wrote a screenplay in accordance with Corman's requirements. Although he was given total directorial freedom during production, Coppola found himself fighting with Corman after the film was completed. The producer declared the movie unreleasable and demanded several changes be made. Corman eventually brought in another director, Jack Hill, to film additional sequences.
One night, while out rowing in the middle of a lake, John Haloran (Peter Read) and his young wife Louise (Luana Anders) argue about his rich mother's will. Louise is upset that everything is currently designated to go to charity in the name of a mysterious "Kathleen." John tells Louise that, if he dies before his mother (Eithne Dunn), Louise will be entitled to none of the inheritance. He promptly drops dead from a massive heart attack. Thinking quickly, the scheming Louise throws his fresh corpse over the side of the boat, where he comes to rest at the bottom of the lake. Her plan is to pretend that he is still alive to ingratiate her way into the will. She types up a letter to Lady Haloran, inviting herself to the family's Irish castle while her husband is "away on business."
Upon arrival, she immediately notices that things are a little strange in the castle. She observes John's two brothers, Billy (Bart Patton) and Richard (William Campbell) taking part in a bizarre ceremony with their mother as part of a yearly ritualistic tribute to their young sister Kathleen, who died many years before in a freak drowning accident. Lady Haloran still mourns for her; and, during the ceremony, she faints dead away as she does every year. As Louise helps her into the house, her mother-in-law tells her that she fainted because one of the flowers she had thrown had died as it touched Kathleen's grave.
Louise, realizing that Lady Haloran is emotionally overwrought and superstitious, devises a plan intended to convince the old woman that Kathleen is trying to communicate with her from beyond the grave. This plan involves stealing some of the dead girl's old toys and placing them at the bottom of the estate's pond where they will float to the surface in the middle of the day in an ostensibly ghostly way. At night, Louise swims into the pond and begins placing the toys as planned; however, she is shocked to see what appears to be Kathleen's perfectly preserved corpse at the bottom of the pond. Horrified, she swims to the surface—and is abruptly axed to death by an unknown assailant. The killer then drags Louise's bloody corpse away.
Concerned family doctor Justin Caleb (Patrick Magee) arrives and becomes determined to solve the mystery. He questions the family in an intense, almost insane manner. Meanwhile, the murderer strikes again, decapitating a man who is poaching on the estate (Karl Schanzer). Dr. Caleb has the pond drained, revealing a stone shrine for Kathleen, with the words "Forgive Me, Kathleen" on the monument. The following night, Lady Haloran is attacked by a shadowy figure, but she eludes him and collapses in the castle's courtyard.
Finally, Dr. Caleb uses an obscure nursery rhyme ("Fishie, fishie, in a brook, Daddy caught you on a hook") recited by Billy under hypnosis to help him discover Louise's corpse hidden in a meat freezer. Next to the body is a wax figure of Kathleen. Dr. Caleb places the figure in a public square to lure the killer. Taking the bait, a gibbering Billy attempts to kill Richard's fiancée Kane (Mary Mitchel) with an axe; he has become insane with guilt over having caused the death of his sister Kathleen. Dr. Caleb removes a gun from his coat pocket and shoots Billy to death.William Campbell as Richard Haloran. Dementia 13 was one of several Roger Corman productions the veteran B-movie character actor appeared in, but it was the first that was completed on such a small budget. Coppola had convinced Campbell (and his The Young Racers co-star Patrick Magee) to appear in the film. The actor originally felt it would turn out to be a strictly "amateur endeavor," but he soon became impressed by Coppola’s leadership abilities, talent, and energy on the set. Campbell recalled years later, "There were all kinds of promises as to what he [Coppola] would do for me later. It was one of those 'I-owe-you-one' things, but he never did anything! I tried to get to him when he was doing The Godfather, thinking that a cop or gangster part might be good for about 17 weeks, but after Dementia 13, I was never able to get through to him again!"
Luana Anders as Louise Haloran. Anders' role as the scheming wife of a rich but prematurely dead heir to a fortune is one of the actress's most notable screen roles. Dementia 13 was one of several appearances she made in AIP productions. Most of these films had been directed by Roger Corman, including a major role co-starring with Vincent Price in The Pit and the Pendulum (1961). Like Campbell and Patrick Magee, Anders had been borrowed by Coppola from the cast of Corman's just completed The Young Racers. After Dementia 13, Anders never had such a sizable role again, appearing in numerous small parts in both television and film until her death from breast cancer in 1996.
Patrick Magee as Dr. Justin Caleb. Magee's role as the family doctor who manages to solve the mystery in Dementia 13 was one of many horror film parts the Tony Award-winning actor accepted during the course of his distinguished career. He had just finished shooting Corman's The Young Racers when Coppola convinced him, along with his Racers co-stars Campbell and Anders, to appear in Coppola's debut feature. Years later, Campbell warmly remembered Magee as being a brilliant performer. although a little prone to overacting.
Bart Patton as Billy Haloran
Mary Mitchell as Kane
Eithne Dunne as Lady Haloran
Peter Read as John Haloran
Karl Schnazer as Simon, the poacher
Ron Perry as Arthur
Derry O'Donovan as Lillian, the maid
Barbara Dowling as Kathleen Haloran
Francis Ford Coppola worked as a sound man on Corman's The Young Racers (1963), a racing film which starred Campbell and Magee. That film was shot in several different countries, and after production was completed in Ireland, Corman still had $22,000 of the film's allocated $165,000 budget remaining. Corman originally thought of using the funds to direct a "quickie" film himself, but his schedule made this impractical. Instead, Corman suggested that Coppola remain in Ireland with a small crew and direct a low-budget horror film, to be produced by Corman. Coppola later recalled, "Roger wanted to make Dementia 13 cheaply. He wanted it to be homicidal, sort of a copy of Psycho. You know, gothic and psychological -- with some kind of terrible knife-killing scene thrown in. So I wrote the script to order."
Coppola wrote a brief draft story idea in one night. The next morning, he described to Corman the most vividly detailed sequence: a half-naked woman ties several dolls to the bottom of a lake, then surfaces to find herself at the feet of an axe murder -- "axed to death!" Coppola exclaimed. Corman was impressed enough to immediately provide Coppola with the $22,000 for the film. The young director was able to arrange an additional $20,000 in financing himself by pre-selling the European rights to a producer named Raymond Stross. Coppola did not inform Corman of the production's additional funding...and quickly moved the initial $22,000 into a bank account in case an angry Corman ever attempted to reclaim his original investment.
Coppola’s friend Al Locatelli served as the film’s art director and helped Coppola write the final script in three days, uncredited. The speed in which the screenplay was completed resulted in unrealistic, “stilted” dialogue that Campbell recalled as being very difficult for the actors to speak.
The majority of the American actors in the cast were friends of Coppola’s from UCLA, and many of them paid their own way to Ireland for the opportunity to appear in a film. Most of the Irish cast members were from the Abbey Theatre and were paid strictly minimum wage salaries. Eithne Dunne received approximately $600 for her performance. Cast and crew lived together in a farm house located outside of Dublin.
Howth Castle, located in the Dublin suburb of Howth, depicted the fictitious "Castle Haloran" in the film.
During the filming, Coppola kept Corman updated on the status of the production in letters that promised lots of sex and violence would be in the film, "enough to make people sick." Coppola was left entirely on his own while directing the film, without interference of any kind from Corman. But after the completed film was shown to him, Corman stormed out of the screening room and demanded that several changes be made to the film that Coppola did not agree with. According to Coppola, Corman "insisted on dubbing the picture the way he wanted it, adding voiceovers to simplify some of the scenes. Worse, he wanted some extra violence added, another axe murder at least..." Jack Hill was later hired by Corman to shoot some brief sequences featuring actor Karl Schanzer as a comical poacher who is beheaded by the murderer.
Corman also complained the film was too short and insisted that it be padded by at least five minutes. Gary Kurtz, one of Corman's assistants at the time, recalled, "So we shot this stupid prologue that had nothing to do with the rest of the film. It was some guy who was supposed to be a psychiatrist, sitting in his office and giving the audience a test to see if they were mentally fit to see the picture. The film was actually released with that prologue." The prologue was directed by Monte Hellman. This cheap William Castle-style gimmick also included a "D-13 Test" handout given to theatre patrons that was ostensibly devised by a "medical expert" to weed out psychologically unfit people from viewing the film. The test consisted of such questions as, "The most effective way of settling a dispute is with one quick stroke of an axe to your adversary's head?" and "Have you ever been hospitalized in a locked mental ward, sanitarium, rest home or other facility for the treatment of mental illness?", with "Yes" or "No" as the only possible answers.
The rockabilly song that is played at the opening of the movie is "He's Caught" by Buddy and The Fads, written by Arthur "Buddy" Fowler. The song was recorded in 1959 in Hollywood, CA. for Accent Records.
The film was released in the fall of 1963 as the supporting feature of a double bill with Corman's X: The Man with the X-Ray Eyes. Because of its rushed production and a somewhat incomprehensible screenplay, reviews of Dementia 13 have been mixed. The New York Times dismissed the film: "Under the stolid direction of Francis Coppola, who also wrote the script, the picture stresses gore rather than atmosphere and all but buries a fairly workable plot." Michael Weldon, in The Psychotronic Encyclopedia of Film, noted it had "[A] great trick ending, some truly shocking, gory axe murders, and lots of inventive photography." Tom Raynes, in the Time Out Film Guide, said "The location (an Irish castle) is used imaginatively; the Gothic atmosphere is suitably potent, and there's a wonderfully sharp cameo from Patrick Magee." Danny Peary, in his Guide for the Film Fanatic, stated that despite the "hopelessly confusing" storyline, "...the horror sequences are very exciting."
Phil Hardy's The Aurum Film Encyclopedia: Horror opined, "[O]ne senses the presence of a director right from the moody opening sequence...A piece of high gothic melodrama...The weakness of the film is in the script, which gives every indication of having been bundled together at the last minute..." John Charles, in Video Watchdog, wrote that the film was "a remarkably confident and proficient thriller. Several of its components hint at the creativity that was still to come from Coppola... and the finished product is a testament to his ingenuity." Kim Newman has opined, "Coppola...works fast and creative in Dementia 13--making memorable, shocking little sequences out of the killings and the implied haunting--using his locations well and highlighting unexpected eeriness like a transistor radio burbling distorted pop music as it sinks into a lake, along with a just-murdered corpse." Dementia 13 has a 65% favorable rating on Rotten Tomatoes, out of 20 reviewers surveyed.
The Roan Group released a laserdisc and DVD of the film, both of which included an audio commentary by Campbell. The DVD also featured the written version of the "D-13 Test" in digital form as an extra; however, the filmed five-minute prologue featuring the test has not been included on any of the numerous available home video versions of the title. On April 26, 2011, the film was released on Blu-ray.