Edmond (Jim Caviezal) is sailing in French waters along with his best ffriend, Fernand (Guy Pearce) , when their captain falls ill. They stop for help at a nearby island, which happens to be where Napolean Bonaparte is in hiding. Bonaparte pulls aside Edmond and asks him to deliver an "innocent letter" to an old ffriend in Marseille, France. Edmond agrees, as that is the price for the use of Napolean's physician. The captain unfortunately dies, so the crew returns home to Marseille. Edmond is made captain for his bravery in seeking a physician, and the first mate comes to despise him for it.
Fernand finds out about the letter, and reads it while Edmond is sleeping, and is angry that Edmond did not tell him about it. Edmond, not knowing that Fernand knows about the letter, rushes to greet his fiance, Mercedes, and tell her that they can now be married as he was just promoted to captain. This is also the point in the movie when you realise that Fernand is in love with Mercedes, but she loves Edmond.
Fernand, still angry, decides to work together with the furious first mate, and get Edmond arrested for treason, which he didn't commit. Fernand works also with a very important magistrate, Villefort, who's father is the man Edmond was to deliver the letter to. (Villefort does not know of this). Thus, Edmond is arrested, and thrown into a remote island prison by the name of Chateau D'if. There, he meets Priest, who teaches him many valuable lessons about life, how to sword fight, and give Edmond a proper education. All this is in turn for Edmond helping to dig, in order to escape the prison.
For 13 years, Edmond is held captive in the Chateau D'if, and unknown to Edmond, a letter was sent to his family and Mercedes saying that he was executed on grounds of treason. Finally, Edmond escapes when the priest dies, and becomes part of a crew on a merchant vessel, along with his good friend Jaccapo. After 3 months, Edmond is released along with Jaccapo, and they go in search of finding out what has happened to Edmond's loved ones. They find out that Edmond's father committed suicide, and the Mercedes wed Fernand a month after learning of Edmond's execution. Edmond has by this time (with the help of the priest while in prison) figured out that he was framed by Fernand and the others. Thus, he and Jaccapo sail to a remote island that the Priest told Edmond about, and there they find a treasure, making Edmond extremely wealthy. Edmond decides to become a count in order to get revenge on those who betrayed him, so he becomes The Count of Monte Cristo, being the treasure he found The Treasure of Monte Cristo.
Soon after, he "saves" Fernand and Mercedes' son Alber from captivity, and thus enters the lives of those he is trying to hurt like they hurt him. Mercedes begins to suspect that The Count is really Edmond, and when she confronts him privately, he denies it but slips and she realises that he really is Edmond. Then, they kiss, and realise that they are still in love, so Mercedes goes back to her Chateau to inform Fernand that she is leaving him, when Fernand tells her that he has gone bankrupt (which is really Edmond's doing, but he doesn't know this) and is leaving the country. (By this time, Villefort has been convicted of murdering his father and sent to jail, also doings of Edmond's). Mercedes precedes to inform Fernand that Alber is not his son, but Edmond's. Fernand becomes angry and goes out to his old, abandoned villa to collect the gold he had supposedly stolen from The Count of Monte Cristo, only to find that it is not there (Edmond's doings, again). Then, Edmond shows up, and tells Fernand where he has been all these years, and they begin a duel, only to be stopped by Mercedes and Alber. Mercedes then tells Edmond that Alber is really his son, not Fernand's. Fernand then shoots Mercedes in the shoulder (she lives) and runs off. Edmond follows him and they begin sword fighting again. Finally, Edmond kills Fernand, and goes back to Mercedes and Alber and Jaccapo. At the very end, Edmond buys the Chateau D'if thanks the Priest for his wisdom and help.