All of the effects are created by renowned horror make-up artist Giannetto De Rossi, a favorite of late director Lucio Fulci.
A woman is wearing a hospital gown, whispering to herself. A reveal of her bare back shows it covered with sutures. Then a woman is running through a forest to a road and with her motions and screams for help stops a car. A reveal of her hand shows that she has just been touching her bloodied stomach. This has been Marie's dream.
She and her best friend, Alex will stay for the weekend and study at Alex's parents' house. Alex gives Marie a tour of the house before dinner. They go to sleep in separate rooms after dinner. The front door is answered by Alex's father; his face is slashed by the man at the door, face pressed between spindles of the staircase then decapitated when a bookcase is shoved along the railing. Alex's mother wakens, finds her husband dead and is approached by the killer.
Marie hears the screams of the mother, arranges her room to make it appear that it is unoccupied then hides under the bed. The killer enters the room and leaves. Marie goes down stairs to find Alex chained to her bed. Marie looks for a phone in Alex's parent's room but is stopped after hearing two loud thuds. She hides in the closet and through the planation-shuttered doors sees Alex's mother's neck slashed by the killer.
Alex's younger brother runs from the house and is pursued by the killer into a cornfield. Marie is with Alex when she sees from a window the brother killed. Marie is unable to free Alex before the killer returns. She goes to the kitchen and gets a butcher knife. The killer drags Alex to his truck. Marie is unnoticed when she makes her way to the truck, hides inside the truck and then the killer locks them inside.
The killer drives to a gas station convenience store where Marie gives Alex the knife and sneaks into the shop for help. The killer enters the shop, Marie is hiding outside and see clerk (Franck Khalfoun) axed to death. The killer drives the truck down a deserted road. Marie follows in the clerk's car and is noticed. The killer pushes Marie's vehicle off the road where it is wrecked. On foot, Marie runs into a forest followed by the killer.
Marie bludgeons the killer with a fence post covered in barbed wire; he grabs at her throat. Marie suffocates him with a plastic sheet and makes her way back to the truck. Alex seems terrified of Marie as she returns to the vehicle. As police investigate the gas station murders via the in-store videotape, the tape shows Marie murdering the store clerk. In retrospect, the audience is shown how the family murders really happened. Finally, the audience discovers that Marie is murderous, delusional, and in love with Alex.
At the truck, Marie unties Alex. As soon as Alex is free, she threatens Marie with the knife and accuses her of butchering her family. Alex slashes Marie's face and stabs her in the stomach before running into the forest. Marie chases Alex with a concrete saw. Alex finds a road and flags down a car. As Alex is climbing into the car, Marie appears brandishing the concrete saw and disembowels the driver. A stray piece of glass slices Alex's Achilles tendon. Alex takes a crowbar from the car's toolbox and crawls along the road. Marie forces Alex to tell her that she loves her, and she kisses her. While engaged in the kiss, Alex plunges the crowbar into Marie's chest as Marie proclaims she'll never let anyone come between them.
The final scene shows Marie in a psychiatric hospital room, and Alex watching her through a one-way mirror. Marie grins and reaches for Alex, aware that she is behind it.Cécile de France as Marie. The protagonist, a college student who attempts to save her friend from a brutal killer before the ending reveals that she is really the murderer. Her motive seems to be her obsessive love for Alex and desire to be alone with her. Marie has created a separate persona (the psychopathic killer) in her mind who murders the victims.
Maïwenn as Alex. The object of Marie's desire. She is terrorized by her own friend.
Philippe Nahon as The Killer. A man sexually obsessed with killing and torturing women. It is revealed that he exists only in Marie's mind. When Marie butchers, she imagines The Killer as a person outside herself. Finally, after she "kills" the alter-ego, Marie and the Killer persona appear alternately.
Andrei Finti as Alex's father. He is killed on the first night, decapitated in a bizarre way.
Oana Pellea as Alex's mother. Her throat is slashed near to decapitation as she tries to use the phone to call for help. The Killer also cuts off her hand for trying to use the phone.
Franck Khalfoun as Jimmy, the store clerk at a gas station. Marie/The Killer murders the clerk with an axe. This murder is captured on a security camera that later reveals the film's twist.
Some scenes were edited for the American version to achieve an R rating by the MPAA. About one minute of the film was cut in order to avoid the NC-17 rating. The R-rated edition was released in American cinemas, and in a less widely circulated fullscreen DVD. This section notes what was deleted from the unrated, original French film to produce the American version.Alex's father is graphically decapitated with a bookcase, his headless neck spraying blood. In the R-rated version, the murder is edited to quickly cut away as the bookcase crushes and severs his head. Later the body is seen on the staircase without the head.
When Alex's mother has her throat slashed, the scene is shortened; most of the arterial spurting, as the killer pulls back her head, is gone. Subsequent shots of Marie inspecting the body have also been edited.
The death of Jimmy the gas station clerk has been shortened. Close-up shots of the axe sticking in his chest have been removed.
The scene where Marie strikes the killer's face with the barbed wire pole is shortened and less explicit; Marie hits the killer fewer times, and fewer details of the killer's wounds are shown.
The driver's disembowelment with the concrete saw was shortened.
A close-up of the crowbar in Marie's shoulder is missing.
High Tension was released in France on 18 June 2003 where it was distributed by EuropaCorp.
The film was shown at the 2003 Toronto International Film Festival during the Midnight Madness section. After screening at the festival, the film was purchased by Lionsgate Films for North American distribution. In her book Films of the New French Extremity, Alexandra West described The screening of High Tension at Midnight Madness made the section of the film festival an "unintentional bastion for New French Extremity" which still did not have a popular following. Following High Tensions's release there, other films followed at the festival such as Calvaire in 2004, Sheitan (2006) and Frontier(s) and Inside (2007) and Martyrs in 2008.
High Tension received mixed reviews in North America; it holds a 41% rating from review aggregator Rotten Tomatoes; the consensus states: "There is indeed a good amount of tension in this French slasher, but the dubbing is bad and the end twist unbelievable." and a score of 42 on Metacritic, classifying it as having received "mixed or average reviews."
Roger Ebert was very negative about the film, giving it one star, saying that it was "poor, nasty, brutish, and short," and that it has a plot hole "that is not only large enough to drive a truck through, but in fact does have a truck driven right through it."
Lisa Nesselson of Variety was more forgiving, saying that the film "deftly juggles gore and suspense," has "unnerving sound design," and "has a sinister, haemoglobin look that fits the story like a glove."
The film was included in TIME Magazine's 10 most ridiculously violent films.
Several viewers of the film noticed striking similarities between the plot of the film and the plot of Dean Koontz's novel Intensity. When questioned at the Sundance Festival in 2004, the director acknowledged that he had read the novel and was aware of the similarities. On his website, Koontz stated that he was aware of the plagiarism but would not sue "because he found the film so puerile, so disgusting, and so intellectually bankrupt that he didn’t want the association with it that would inevitably come if he pursued an action against the filmmaker."Muse — "New Born"
Ricchi e Poveri — "Sarà perché ti amo"
U-Roy — "Runaway Girl"
Félix Gray and Didier Barbelivien — "A toutes les filles"
François Eudes-Chanfrault — "Faustina Mauricio Mercedes"
Scott Nickoley, Jamie Dunlap, Molly Pasutti, and Marc Ferrari — "I Believe"
François Eudes-Chanfrault — "Celebration A2"
Arch Bacon — "Pillow Talk"
François Eudes-Chanfrault — "Paris—Nice"
François Eudes-Chanfrault — "Out of the Mundial"