Charles Schine, played by Clive Owen, is an advertising executive based in Chicago, whose intense story unfolds as an unidentified man documents it from a prison cell. A series of flashbacks reveal Charles's turbulent home life, where he grapples with a crumbling marriage and the challenges of his daughter’s diabetes, which necessitates costly medication.
While commuting, Charles meets the captivating Lucinda Harris, portrayed by Jennifer Aniston, a married financial adviser. An undeniable attraction sparks between them, leading to frequent clandestine meetings. The tension culminates in a rendezvous at a shabby hotel, where their affair takes a dark turn. An armed intruder, later known as Philippe LaRoche, played by Vincent Cassel, storms in, violently assaults Lucinda, and leaves Charles battered.
In a pact of silence to protect their spouses from discovering the affair, they decide against reporting the incident. However, things escalate when LaRoche blackmails Charles, initially demanding $20,000 and subsequently increasing the ransom to $100,000 while threatening his family. Desperate, Charles confides in Winston Boyko, an ex-con portrayed by RZA, who proposes to intimidate LaRoche for a fee. In a moment of desperation, Charles embezzles $10,000 from his workplace to pay Winston.
Tragically, Winston is murdered by LaRoche, prompting an investigation led by Detective Franklin Church, played by Giancarlo Esposito. Just when things couldn't seem worse, LaRoche contacts Charles and reveals that he has Lucinda at gunpoint, demanding the remaining sum. To save her, Charles uses funds set aside for his daughter’s medical expenses, bidding a heart-wrenching goodbye to Lucinda after handing over the money.
In a shocking twist, Charles discovers that the woman he fell for on the train was not Lucinda but Jane, a lookalike temp. Realizing he has been duped, he tracks Jane and catches her in a compromising position with LaRoche. Determined to reclaim his stolen $100,000, he confronts Jane and her accomplices at a hotel, leading to a gripping shootout where he emerges as the sole survivor.
Though he retrieves his money, Charles faces arrest for the embezzlement he committed to pay Winston. His sentencing involves six months of community service, during which he comes across a story about himself that was being penned at the film's outset. The narrative takes a climactic turn when he discovers LaRoche, who survived their earlier encounter, leading to a final confrontation that leaves LaRoche dead at Charles's hands.
Ultimately, as Charles steps into the outside world, he crosses paths with Detective Church once more. Although the detective harbors suspicions, he allows Charles to return to his family, setting the stage for a life forever altered by the choices he made.
