Starring Monica Bellucci , Vincent Cassel , Albert Dupontel , the plot depicts the events of a tragic night in Paris as two men attempt to avenge the brutal rape and beating of the woman they love. The film is made up of a title sequence followed by 13 segments made to look like long takes. Each of these segments is either a continuous shot or a series of shots digitally composited to resemble a continuous shot.
The story is told in reverse order , with each scene taking place chronologically before the one that precedes it. Alex and Marcus, a young couple, wake up together and discuss their relationship, as well as an upcoming party, while in the nude. Alex reveals she had a dream of herself standing in a red tunnel that breaks in two, before taking a pregnancy test that reveals a positive result.
On a public train, Pierre, Alex's ex who is also invited to the party, constantly bickers with Alex over his inability to satisfy her during their relationship, while Marcus shows no interest in their squabble. At the party, Marcus gets drunk and takes cocaine, much to Alex's displeasure. She leaves the party, asking Pierre to look after Marcus. Alex descends into a red pedestrian underpass on her way back to the train when she notices a transgender prostitute getting attacked by a man.
He immediately turns his attention to Alex, anally raping her before savagely beating her into unconsciousness. After Marcus and Pierre discover Alex being taken away by paramedics, they encounter street criminals Mourad and Layde, who offer to help them find the culprit. They use an ID left at the scene by the prostitute to locate her.
The men are chased off by other prostitutes; Marcus and Pierre jump into a taxi cab and speed off into the night. When the cab driver doesn't know where Rectum is, Marcus attacks the driver, stealing his vehicle. The two end up finding Rectum, with Pierre reluctantly following behind Marcus. Pierre comes to his rescue and beats the man to death with a nearby fire extinguisher as the man's companion, the actual rapist, watches in amusement.
