Derailed

Charles Schine (Clive Owen), is an advertising executive. His marriage to Deanna (Melissa George) is deteriorating, and his daughter Amy (Addison Timlin) suffers from diabetes, requiring expensive medication. Charles's story is being written down by an unidentified man in a prison cell.
On a commuter train, Charles encounters an alluring woman named Lucinda Harris (Jennifer Aniston). She is a married financial adviser. The two show each other photographs of their respective daughters and begin to talk. A mutual attraction develops, and the two begin meeting frequently. Ultimately, they decide to consummate their affair and wind up in a seedy hotel. An armed manâlater identified as Philippe LaRoche (Vincent Cassel)âbursts into the hotel room, beats Charles, and brutally rapes Lucinda. Charles and Lucinda agree not to report the crime, as they do not want their spouses to learn of the affair. Shortly after, Charles is blackmailed by LaRoche, who threatens to kill his family if he does not pay $20,000, which Charles promptly pays. A month later, the attacker calls again, this time demanding $100,000.
Charles explains his situation to Winston (RZA), an ex-con who works as a repairman in his building and whom Charles had earlier befriended. Winston offers to scare off LaRoche for ten percent of the payout. Charles agrees and embezzles the money from his company. He and Winston travel to the meeting location specified by LaRoche, intending to get the drop on him. However, before they can act, Winston is shot and killed. LaRoche appears and takes the money, leaving Charles to dispose of the body. Afterwards, Charles is questioned by detective Franklin Church (Giancarlo Esposito) about Winston's murder. Later, Charles receives a call from LaRoche who claims that he will kill Lucinda if Charles doesn't deliver the $100,000. Charles takes the money from an account meant for his daughter's medical treatment and makes the payoff.
The next day, Charles stops by Lucinda's company to ask to see her and is introduced to the real Lucinda Harris. The woman he met on the train is identified as Jane, a temp who had worked there briefly. He goes to Lucinda's apartment, which he realizes is actually in the process of being rented out. Seeing that Lucinda's photograph of her daughter was actually a cut out of a stock picture in a brochure, Charles realizes Jane was in on the scam. He tracks her down and sees her kissing LaRoche. Determined to retrieve his stolen money, he follows Jane's moves and sees that she is seducing another unsuspecting businessman (David Morrissey). He rents a room in the same hotel where Jane, LaRoche, and their partner Dexter (Xzibit) set him up and awaits them as they snare their new target. Jane and the businessman go to the room, but Charles knocks LaRoche unconscious before he can follow them. Charles breaks in and demands the return of his money. A gunfight ensues, and everyone is shot but Charles, who watches Jane die. Charles, while in his rented room, is cleared by the police near the crime scene. As he leaves the hotel lobby, the continued investigation has all contents from the hotel safe laid out on the front desk. Charles casually identifies his briefcase, which still contains his money, and quietly leaves the hotel.
Charles is later accused by his boss Eliot (Tom Conti) of stealing money from the company, and he is arrested for embezzling the $10,000 that he paid Winston and is sentenced to six months of community service, teaching in a prison. During one of his classes, he comes across the story about him written on one of the students papers. The unknown writer instructs him to go to the laundry room. There, Charles finds LaRoche, who survived the gunfight. LaRoche threatens to continue to disrupt Charles's life, but Charles reveals that he has planned the encounter. He produces a shank, which Winston had given him, and stabs LaRoche to death. As Charles leaves, he encounters Detective Church who indicates that he knows LaRoche killed Winston. While Church suspects Charles of killing LaRoche, he lets him return to his family, where Charles reconciles with his wife and daughter.

Question: Who was in on the scam?
Answer: Jane.