Two shadowy figures struggle until one of them is stabbed to death while a child's scream is heard.
In the city of Rome, psychic medium Helga Ulmann (Macha Méril) holds a lecture in a theater where she senses that there's someone with a twisted and violent mind in the audience that she cannot clearly identify. Later that night, while Ulmann is in her apartment taking notes about the incident in the theater, someone kicks the door in and murders her with a meat cleaver, also destroying her notes in the process. Musician Marcus Daly (David Hemmings), who lives in the same apartment building is walking home when he sees her being attacked through the window. Rushing inside to help, he's too late as Helga bleeds to death.
After the police arrive, Marcus realizes he had seen a certain painting among a group of portraits on the walls of the victim's apartment, which seems to have disappeared. Helga's is prefaced by a child's doggerel tune, which serves as the murderer's calling card. Marcus hears it in his own apartment soon after becoming involved in the case, and is able to foil the murderer by locking himself in his study. Later, he plays the tune to Professor Giordani (Glauco Mauri), a psychiatrist who theorizes that the music is important because it probably played an integral part in a traumatic event in the killer's past. Another friend of Ulmann tells him about a folktale involving a haunted house in which a singing child is heard, followed by the shrieking of someone being murdered.
Investigating the source of the music tune and the folktale, the search leads Marcus to a story from a book written by Amanda Righetti (Giuliana Calandra), titled House of the Screaming Child which describes a long-forgotten murder. Marcus tries to find Amanda to talk to her about her book, but the unseen killer arrives at her villa first and kills her by drowning her in a bathtub filled with scalding hot water. The dying Righetti manages to write a message on the wall of the steam-filled bathroom before expiring. Marcus then finds the body but afraid that the police will think he did it and leaves the place without calling anyone. Thanks to a picture from the book, Marcus locates the house where the folktale originated and learns from the caretaker that no one has lived in the house since 1963 when the previous owner disappeared. Marcus looks around the house, removing plaster from a wall that uncovers a child's drawing of a little boy holding a bloody knife next to a murdered man and a Christmas tree. Only after he leaves the room, more plaster suddenly falls off, revealing a third figure in the drawing.
Meanwhile, Giordani investigates the Righetti murder scene and, on a hunch, turns on the hot water in the bathroom and sees part of the message left on the wall by the murder victim. When Giordani returns to his office that night to investigate more, when he's distracted by a laughing clown toy. The unseen killer then breaks in and stabs him in the neck with his own knife after bashing his teeth in on a mantelpiece. Marcus also discovers a clue that he initially overlooked in the photo of the deserted house realizing a window on one of the walls is missing. Marcus returns to the house after dark after unsuccessfully bashing in the wall where the window was (which leads to him nearly to fall off the ledge) when he enters inside. Using a pickaxe, he knocks down an end-wall in a hallway and discovers the secret room with a skeleton next to a Christmas tree. The unseen figure then arrives and knocks Marcus unconscious. The house is set on fire, but Marcus is dragged out by Gianna (Daria Nicolodi), a reporter investigating the murders.
Marcus and Gianna go to the caretaker's house to call the authorities. There, Marcus discovers the caretaker's young daughter Olga has drawn an identical drawing of the little boy with a bloody knife standing next to a murder victim. Olga tells them she copied the drawing from an old file in the archives at her junior high school. Marcus and Gianna then break into the school to search the archives for the drawing. Marcus finds the painting, which has the name of Marcus' friend Carlo (Gabriele Lavia) on it. He looks for Gianna and finds she has been stabbed. Carlo suddenly appears before Marcus holding a gun and threatens to kill him for getting too close to the truth. Just as the police arrive, Carlo flees and climbs over a wall only to get hooked onto a rebar transported by a passing truck and is dragged down the street to a gruesome death.
The case is apparently wrapped up with Carlo being the killer. After Marcus drops off the wounded Gianna at the hospital, he heads back to the scene of the crime, he realizes that Carlo could not have murdered Ulmann because they were together only for a few seconds before Marcus saw her at the window. Marcus then enters the murder victim's apartment and after looking around, finally remembers what he saw in a mirror reflection which he thought was a portrait that night is the face of the killer. When he turns back, the killer appears in front of him, finally revealed to be Carlo's insane mother Martha. In a flashback, Carlo is still a child and witnesses his mother stabbing her husband because he tried to have her committed to psychiatric hospital. Carlo, traumatized, picks up the bloody knife and stares at it, then Martha entombs her husband's body in a room of the house.
In the climax, Martha confronts Marcus and tries to kill him by wielding a meat cleaver as she chases him out of the apartment to an elevator. Marcus is then struck in the shoulder by the meat cleaver, but manages to kick Martha toward the elevator shaft. When the long necklace she's wearing gets caught in the bars of the shaft, she's decapitated when he pushes the elevator button. The film ends with Marcus staring a pool of Martha's blood.
Deep Red was shot mainly on location in Turin, Italy – a "magical" city according to Argento – in sixteen weeks. The main reason why he chose Turin was because at the time there were more practicing Satanists in Turin than in any other European city, excluding Lyon. Argento's original working title for the film was La Tigre dei Denti a Sciabola (The Sabre-Toothed Tiger)
Co-writer Bernardino Zapponi said the inspiration for the murder scenes came from Argento and himself thinking of painful injuries to which the audience could relate. Basically, not everyone knows the pain of being shot by a gun, but almost everyone has at some point accidentally struck furniture or been scalded by hot water. The close-up shots of the killer's hands, clad in black leather gloves, were performed by director Dario Argento himself. The film's special effects, which include several mechanically operated heads and body parts, were made and executed by Carlo Rambaldi.
Two key sequences in this film influenced directors of later horror movies. David Cronenberg's Scanners has the famous head exploding scene that is modeled after the Parapsychology discussion at the beginning of Deep Red, and Rick Rosenthal's Halloween II (1981 film) contains a scalding water death that bears a striking resemblance to actress Amanda Righetti's demise in her bathroom.
In a contemporary review, Vincent Canby wrote in The New York Times referred to the film as a "bucket of ax-murder-movie cliches" and referred to Dario Argento as "a director of incomparable incompetence."
From retrospective reviews, Kim Newman wrote in the Monthly Film Bulletin that Deep Red was a transitional work for Argento between his earlier whodunit plots and the more supernatural themed films. Newman concluded that Deep Red is "nothing if not an elaborate mechanism, with the camera crawling among objets trouvés" and "what sets Argento apart from imitators like Lucio Fulci is his combination of genuine pain (the murders are as nasty as one could wish, but the camera flinches where Fulci's would linger) and self-mocking humour" Total Film gave the film four stars out of five, noting that Argento's films "can be an acquired taste; it’s necessary to attune yourself with the horror director’s style in order to get the most from his movies." The review stated that the film "presents some striking visual compositions that raise it above the level of the usual subgenre offerings." and that the film was "A great introduction to Dario Argento’s evolving style of horror". The A.V. Club wrote, "Operating under the principle that a moving camera is always better than a static one – and not above throwing in a terrifying evil doll – Deep Red showcases the technical bravado and loopy shock tactics that made Argento famous." AllMovie compared the film to other in Argento's work, noting that the film script was "significantly stronger and the actors much better" AllMovie noted that "Each of the murders is perfectly choreographed with particular praise going to Glauco Mauri's killing" and that "The final reel wraps the film up in a thrilling manner and features two extremely graphic deaths that leave the viewer stunned as the credits roll"
The film currently holds a 95% approval rating on review aggregation website Rotten Tomatoes, based on 22 reviews with an average rating of 8.2/10. The site's consensus reads: "The kinetic camerawork and brutal over-the-top gore that made Dario Argento famous is on full display, but the addition of a compelling, complex story makes Deep Red a masterpiece."
Multiple versions of the film exist on DVD and VHS, in large part due to the fact that Argento removed twenty-six minutes (largely scenes between Nicolodi and Hemmings) from the film, footage that was never dubbed in English. For years, it was assumed that the film's American distributors were responsible for removing said scenes, but the recent Blu-ray release confirmed that Argento oversaw and approved the edits to the film.
Eleven seconds of animal cruelty cuts made to the film by the BBFC in 1993 were waived when the film was re-submitted in 2010.
In 1999, Anchor Bay acquired the rights to release the film uncut on both DVD and VHS. Their version restored the missing footage but kept the American end credit scene (a freeze-frame shot of Hemmings looking down into a pool of blood). As there were no dubbed versions of the missing scenes, the scenes (and additional dialogue omitted in the dubbed version) were featured in their original Italian language. The DVD offered both English and Italian audio tracks as well.
Blue Underground obtained the rights to the film in 2008 and released it as a standard DVD. Their Blu-ray release, released in 2011, contains the US version of the film (which is referred to as "The Director's Cut") and the original edit (referred to as "Uncut" and contains option to watch it in either language).
Arrow Films, a distributor of the United Kingdom, acquired the rights to the film and released it on January 3, 2011. The 2-disc set was released uncut as part of the now out-of-print window slip cover sets which released a number of films by Argento and other directors; it contained several special features including interviews, a documentary, trailers, audio commentary, four cover artwork designs, an exclusive collector's booklet written by Alan Jones on the film, and a double-sided poster. Both the director's cut and the theatrical cut are available on the set with an English and Italian audio track, and English subtitles. On January 25, 2016, Arrow Films released Deep Red in a 3-disc Limited Edition set of 3000 copies. The edition is available in new 4K restoration, with new commissioned artwork exclusive from Arrow Films. The original version of the film, as well as US cut are available, with new special features including a soundtrack CD featuring 28 tracks, 6 lobby cards, double-sided poster, reversible sleeve, and a limited edition booklet written by Mikel J. Koven. Bonus features from the previous edition are also included. A standard version of the Limited Edition was released on May 30, 2016 in a single-disc set and contains only the director's cut/original version. Special features from the edition are available.
On November 6, 2013, Australian distributor, Umbrella Entertainment made the film available with both the director's cut and the theatrical cut included.
Argento originally contacted jazz pianist and composer Giorgio Gaslini to score the film; however, he was unhappy with Gaslini's output. After failing to get Pink Floyd to replace Gaslini, Argento turned back to Italy and found Goblin, a local progressive rock band. Their leader Claudio Simonetti produced two compositions within just one night. Argento signed them immediately, and they ended up composing most of the film's musical score (three Gaslini compositions were retained in the final version). Subsequently, Goblin composed music for several other films by Dario Argento.The original Italian version is 126 minutes long. Most US versions remove 22 minutes' worth of footage, including the most graphic violence, all humorous scenes, almost all of the romantic scenes between David Hemmings and Daria Nicolodi, and part of the subplot regarding the house of the screaming child.
The US video release by Anchor Bay Entertainment is mostly restored, reinstating gore shots and scenes with dialogue that were cut from the initial US release. It was likely that these scenes were cut before the English dub was prepared, so they now only exist with an Italian dub (English subtitles are provided for these scenes). In the original theatrical version, the end credits are displayed over a shot of Marcus' reflection in a pool of blood. The image is moving (blood drips into the pool, Hemmings' face changes expression, etc.) while the credits are displayed. Anchor Bay's release features the credits over a freeze-frame of the original shot. Other than this change, the Anchor Bay VHS/DVD is the full, uncut version of the film.
The later DVD release from Blue Underground is the exact version mentioned above. Also, Blue Underground released an "Uncensored English Version" on DVD on 17 May 2011. This cut of the film runs no more than 105 minutes, with the gore from the original Italian version intact but the other cuts from the edited English version again excised.
Unusually the film had no UK theatrical release. The 1993 Redemption video was cut by 11 seconds to remove a brief scene of two dogs fighting and shots of a live lizard impaled with a pin. The 2005 Platinum DVD issue was pre-cut (to exclude the shot of the lizard) and restored the dog sequence (as it was evident that they were playing rather than fighting). It was finally passed uncut for the 2010 Arrow DVD release.
The full-length Italian version (with English subtitles and one small cut by UK censors) is available on video in the UK in pan and scan format from Redemption Films. The only known widescreen print of this version can be found in Australia on both SBS TV and its pay-TV channel World Movies, completely uncut. (Note that the widescreen laserdisc release is in English language and was cut by director Argento himself by about 12 minutes).
Some releases of the film incorporate a still from the film, revealing the murderer.
In 2010, George A. Romero was contacted by Claudio Argento to direct a 3D remake of Deep Red, which Claudio said would also involve Dario. Romero showed some interest in the film; however, after contacting Dario – who said he knew nothing about the remake – Romero declined Claudio's offer.