This youthful romantic tale follows the loves and losses in the life of Jai. At the outset, it is revealed that somebody has emptied the bank accounts of many people, including Babu Anna (Akhilendra Mishra), an underworld don, via an Internet theft. The police are clueless about the robber, while Anna wants revenge. In another story, Jai Malhotra (Shahid Kapoor) lives with his best friend, Sonia (Kim Sharma). He meets Neha Mehra (Kareena Kapoor) and falls in love with her instantly. At first Neha rejects Jai, but later she falls for him too.
One day, Jai sees Neha trying to hang herself after getting a phone call. She tells him that her dead father owed money to Babu Anna's gang. In order to repay the amount, her father had no other choice than to become part of a gang of criminals who were responsible for the Internet thefts. After his death, the gang is now pursuing Neha to recover the money.
Jai spots a rich man named Vikram Singh (Fardeen Khan) and decides to steal money from him. However, Vikram catches Jai. On learning the whole story, Vikram reveals that he is also a part of the gang and agrees to help Jai. In return, Jai has to take the blame for the thefts. Jai agrees, gives the money to Neha and turns himself in. Jai is to be presented for the trial, but Anna has sent his men to kill Jai. The bid fails and Jai runs to Neha's apartment, only to find both Neha and Vikram waiting for him. He is horrified to learn that they indeed stole all the money and Neha's love was just a ruse to con him to take a fall.
Jai escapes from the apartment, but is shot by a police officer in the train. Even though his body isn't found, he is presumed dead. One month later, Neha and Vikram start getting anonymous phone calls. Neha believes that the calls are from Jai and that he is still alive. Jai, and bent on getting revenge on both Neha and Vikram.
Jai makes life miserable for both Vikram and Neha. One day when Neha and Vikram go out for a movie, Vikram finds Neha hanging by her neck in the toilet, and Neha confirms that Jai is alive. He tricks them in such a way that Anna too gets a whiff of the affair. In the end, Anna holds all three of them hostage and demands his money. Jai cleverly deflects Anna and forces Vikram to transfer Anna's money back into his account. Catching him unawares, Jai and Vikram finish Anna and his gang.
In the melee, Vikram has Jai cornered. After the shootout is over, Vikram and Neha mock at him. Vikram guns down Jai. Jai takes Babu Annas gun and shoots Neha in the forehead. After Jai mocks at Vikram and dies. Later, a news reveals that somebody has made a very hefty and generous donation to the PM's Relief Fund. Vikram is shown heading somewhere in a boat in the end.