context: In 2006, the illegal drug trade based in Kuala Lumpur is booming. The Malaysian authorities are called upon for assistance by their Indian counterparts. The Indian team sent to Kuala Lumpur is headed by Deputy Commissioner of Police De Silva (Boman Irani), who targets the illegal drug operations of Singhania (Rajesh Khattar). Helping him along the way is Inspector Vishal Malik (Om Puri), an Indian officer from Interpol. Both of them know that in order to put an end to the illegal drug trade, they must capture "Don" (Shah Rukh Khan) who manages Singhania's business in Kuala Lumpur. Singhania was one of the two closest and most trusted men of Boris, a criminal who went underground and was presumed dead by the police. Boris's other lieutenant was a man called Vardhan, equally ruthless as Singhania, but his whereabouts are unknown. De Silva explains that Singhania had killed Vardhan upon learning that Boris was about to hand over his drug business to Vardhan.
  Singhania's subordinate, Don, is known for murdering one of his close associates, Ramesh (Diwakar Pundir), who had attempted to leave the cartel. Ramesh's future wife Kamini (Kareena Kapoor) decides to help the police arrest Don but in the process she is also killed. Now, Ramesh's sister Roma (Priyanka Chopra) plans to avenge her brother and his fiancÃ©. She manages to infiltrate Don's gang.
  Don and his inner circle, which consists of Anita (Isha Koppikar) and Narang (Pawan Malhotra), travel to India for a cocaine transaction. An Indian police team led by De Silva follow them there and capture Don, who is fatally injured while trying to flee from the police. De Silva keeps this a secret from the department and media as he decides to track down an exact look-alike of Don named Vijay (Shah Rukh Khan) from Mumbai, asking Vijay to pose as Don so the police can get to Singhania. Vijay agrees when De Silva promises to admit Deepu (Tanay Chheda), a kid Vijay looks after, to a school in Kuala Lumpur.
  Meanwhile, Jasjit (Arjun Rampal), Deepu's father, has just been released from prison. Jasjit is hellbent on killing DCP De Silva. Jasjit's vendetta against De Silva began many years ago, when Jasjit, committing a crime in order to save his family from a gang of criminals, was arrested on the orders of De Silva, thereby preventing Jasjit from saving his wife from death. Jasjit does not know what happened to his son after Jasjit went to prison. It is implied that the criminals responsible for the death of Jasjit's wife were none other than De Silva's own men.
  Vijay is admitted to the same hospital as Don by De Silva. Vijay soon gets all the scars and marks which Don has on his body. Suddenly, Don dies of heart failure and the masquerade becomes inevitable. When Vijay (as Don) re-enters the gang in Kuala Lumpur, he claims to have lost his memory, and the more he learns about Don, the more he claims to remember. Don has a disc containing some of the cartel's vital information about deals and contacts. As part of the plan, Vijay agrees to find and bring this disc to D'Silva. When Vijay finds the disc, Roma (who is now a close associate of Don) decides to accompany him. When they arrive, Roma attempts to kill Vijay (assuming he is Don). However, DCP De Silva intervenes and tells Roma about his secret plan to reach to Singhania. Roma decides to help the police to capture Singhania and joins the two in their plan. Vijay hands over the disc to DCP De Silva.
  Singhania comes to Kuala Lumpur for a meeting with his clients. There DCP De Silva murders him by adding poison to his drinks, and then stabbing him. Suddenly, the Malaysian police and Interpol arrive at the hotel. Vijay and the core gang members are all arrested by Interpol. De Silva is apparently killed in shoot-out. This is unfortunate for Vijay because De Silva was the only person who could prove that Vijay is not the real Don. Vijay also tries to use the help of Dr. Ashok Gilwani, the doctor who operated on him to get all of Don's scars and marks that Don had on his body, but is shocked to hear that even he is dead after a car accident one month earlier. Now Don's inner circle turns against Vijay, having discovered his true identity. Vijay escapes from police custody and tries to recover the disc he gave to De Silva in order to prove his innocence.
  Jasjit secretly enters DCP De Silva's apartment in Kuala Lumpur and waits for De Silva with a gun, not knowing of his death. There Jasjit finds the disc Vijay gave to the DCP and is shocked by its contents. He soon receives a phone-call saying that if he wants to see his son again, he will have to bring the disc to the men who have Deepu, his son, hostage. At this meeting, it is revealed that DeSilva was alive all along and is actually Vardhan, Boris' other lieutenant. In other words, Vardhan, posing as De Silva, used Vijay to get closer to Singhania and eliminate his competitor. Jasjit somehow manages to escape with his son from the smugglers.
  Jasjit meets Vijay [now at large] and Roma and reveals that De Silva is really Vardhan. With this knowledge the three hatch a plot to help Interpol arrest Vardhan. The next day, Jasjit arranges a meeting with Vardhan in Langkawi, saying he will hand over the disc. The trio inform the Malaysian police and Interpol of the meeting and get Vardhan arrested. Vijay is fighting a final hand-to-hand combat with Vardhan. He prepares to kill him, but stops at Mr. Malik's pleads and is rushed to hospital. Vardhan is arrested. Vijay is acquitted. Before Vijay leaves, Roma confesses her love for him.
  In a final twist, it is revealed that Don was alive all this time, and was pretending to be Vijay the whole time. While in the hospital, Don recovered quickly from his injuries, overhearing Vardhan's conversation with Vijay. After Vijay's operation, Don got up from the room where Vardhan and Ashok were absent and went to the room where Vijay lay. He switched places with Vijay, taking Vijay off life support and causing him to die of heart failure. It is also revealed that the disc Don gave to the police was fake. Now with both Vardhan and Singhania removed from his path, Don becomes the master of the entire Asian drug dealing ring.
question: Who returned as DON when original DON died?
answer: Vijay