''Haute Tension'' (''High Tension'', also known as ''Switchblade Romance'' in the UK) is a 2003 French horror film directed by Creator/AlexandreAja and staring Cécile de France, Maïwenn Le Besco and Philippe Nahon.

Marie (de France) and Alex (Besco), are two college students and longtime friends on their way to stay at Alex's parent's house for the weekend so they can study in peace. In the night, however, an insane truck driving SerialKiller (Nahon) comes to the house and murders Alex's family. He then abducts Alex herself. Marie goes after her with the intention of rescuing her, [[TwistEnding but it turns out the killer is not who he seems]]...

Critical reception was mixed to negative, with criticism generally being directed at the twist ending which, as much as it might make Creator/MNightShyamalan proud, also generates a gaping PlotHole.

The original version was rated NC-17, and some bits had to be cut for it to be rated R.

!!This films provides examples of:

* ChainsawGood: Both the killer and Marie get a turn with a circular saw.
* ADateWithRosiePalms: Marie, after seeing Alex showering through the bathroom window earlier that night. Since she's listening to her walk-man during the act, this prevents her from hearing the killer get into the house until the murders are well under way.
* FinalGirl: Subverted, in that the protagonist [[spoiler: is ''also'' the killer, leaving both Alex and the killer alive in the end.]]
* {{Foreshadowing}}: There is a lot of this, thought most is nigh impossible to register without knowing the PlotTwist... and some even then.
* GirlWithPsychoWeapon: During the film Marie is depicted wielding both a wooden club wrapped in barbed wire (as shown above) and a circular saw.
* {{Gorn}}: There is a lot of blood in the film and the killings are shown in loving detail in most cases.
* GoryDiscretionShot: While Alex's parents are shown to be brutally killed on screen, the audience only sees a glimpse of gunfire when the killer shoots Alex's kid brother in a corn field.
* TheKillerInMe: [[spoiler:The killer is Marie's alternate personality]].
* ALoveToDismember: Near the start of the film, the killer fellates himself with a woman's severed head.
* MadnessMantra
--> ''"I won't let anyone come between us anymore, I won't let anyone come between us anymore..."''
* NotSoDifferent: The killer seems to be implying this to Marie when he says of Alexia "She turns you on, doesn't she? She turns me on too..." [[spoiler: Of course the killer ''is'' Marie, so...]]
* PsychoLesbian: [[spoiler:Marie's obsession with Alex fuels her alternate personality, who kills Alex's family to eliminate obstacles]].
* SerialKiller: The truck-driving killer might be one. He has killed at least one person before targeting Alex's family, and furthermore, is shown to keep photographs of different women by the mirror in his truck.
* SlasherMovie: A strange example, as it seems to almost turn into an action movie at around the midpoint.
* TwistEnding: [[spoiler:The killer is in fact Marie; the truck driver is an alternate personality whom her normal side perceives as a seperate being, à la ''Film/FightClub''. Marie had a lesbian crush on Alex, and her alternate personality murdered her family so nobody could come between them though she, believing the alternate personality to be a different person, would not have to feel any guilt.]]
* UnreliableNarrator: The primary viewpoint character is Marie, [[spoiler:who is also the killer]].
* VisualPun: [[spoiler:Both of Marie's personalities came at the same time.]]
* {{Yandere}}: The killer wants Alex all to themself, and is not opposed to brutally murdering her entire family to do it, and everyone that comes across afterwards. Unfortunate drivers on forest roads beware.