Director: Farhan Akhtar
Writer: Salim Khan
Stars: Shah Rukh Khan as Don/Vijay
Priyanka Chopra J. as Roma
Arjun Rampal as Jasjeet Ahuja
Boman Irani as Deputy Commissioner of Police De Silva, alias Vardhan, the main antagonist
Isha Koppikar as Anita
Om Puri as Inspector Vishal Malik
Kareena Kapoor Khan as Kamini (special appearance)
Pavan Malhotra as Narang
Rajesh Khattar as Singhania
Tanay Chheda as Deepu Ahuja
Satyajit Sharma as Mystery man
Chunky Pandey as T.J.
Sushma Reddy as Geeta
Diwakar Pundir as Mumbai Police constable Shinde
The illegal drug trade based in Kuala Lumpur, Malaysia is booming. A team headed by Deputy Commissioner of Police De Silva targets the operations of Singhania to capture his manager, Don. Singhania is one of the two lieutenants of a deceased kingpin, known as Boris; the other is Vardhan, whose whereabouts are unknown.
Don kills Ramesh, one of his close associates, after he tries to secretly leave the gang. Ramesh’s fiancée Kamini decides to help the police. She uses herself as bait in an attempt to seduce Don and leave him defenseless against the police. Don knows of her plan and takes her hostage, killing Kamini in the process.
Planning to avenge her brother, Ramesh, and sister-in-law Kamini, Roma infiltrates Don’s gang. Don is injured and falls into a coma while trying to flee from the police. De Silva finds a look-alike named Vijay and asks him to join his mission. Vijay agrees when De Silva promises to admit Deepu, a boy Vijay looks after, to school. Meanwhile, Jasjit an information technologist and Deepu’s father, is released from prison. He plans to kill De Silva to avenge his own wife’s death. Many years ago, after Jasjit returned from work, he was captured by an unknown assailant who made a deal with him to commit a crime in order to save his kidnapped wife. However, De Silva caught him and tried to flee but was shot in the leg and his wife died after he failed and was arrested.
At the hospital, a doctor gives Vijay scars identical to Don’s. When Don suddenly dies, the masquerade begins. Vijay, posing as Don, joins the gang. De Silva asks Vijay to find a computer disc containing details about the drug cartel and bring it to him. When Vijay finds it, Roma attempts to kill him but De Silva tells her of Don’s real identity and she agrees to help. Vijay hands over the disc to De Silva. De Silva murders Singhania and the police arrest Vijay. De Silva is killed in the shootout, devastating Vijay, as De Silva was the only person who could prove that he is not the real Don. Having discovered his true identity, Don’s associates turn against him. Vijay escapes and meets with Roma to recover the disc and prove his innocence.
Meanwhile, Jasjit finds the disc in De Silva’s apartment. He receives a call and is told that he will have to bring the disc to the men who are holding Deepu hostage. He learns that De Silva has been alive all along and is actually Vardhan, Boris’s other lieutenant, who was using Vijay to reach Singhania. Jasjit teams up with Vijay and Roma and reveals De Silva’s true identity. The trio come up with a plan and inform Interpol.
In combat, Vijay overpowers Vardhan and is about to kill him but is interrupted by Inspector Vishal Malik, who has Vardhan arrested. Vijay is acquitted and Roma confesses her love for him. Too late she realizes, in a final twist, that she was being toyed with: Don is alive and was pretending to be Vijay this whole time. At the hospital, Don had recovered from his injuries and overheard Vardhan and Vijay’s plan. After Vijay’s operation, Don switched places with him and injected an overdose of diazepam in Vijay’s glucose stream, causing the latter to die. The disc Don gave to the police was fake. Now, with both Vardhan and Singhania removed, Don becomes the master of the Asian drug-dealing ring.