The movie starts in the winter of 1990 when "The Great Indian Circus" owned & run by struggling single father Iqbal Haroon Khan (Jackie Shroff) in Chicago, Illinois gets foreclosed by the Western Bank of Chicago (which has lent money) when he is unable to repay his loan. His young son Sahir (Siddharth Nigam) begs Anderson not to shut down the circus, insisting that that they will soon foot the bill. After a show stopping performance before the high-handed bankers and despite Sahir's futile pleas, Iqbal gets rebuffed and immediately commits suicide by blowing his own brains out with a targeted head-shot in front of Sahir and the corrupt bankers, including heartless Chairman Warren Anderson, leaving Sahir devastated.23 years later, a vengeful Sahir (Aamir Khan) frequently robs various branches of the Western Bank of Chicago, leaving behind a message in Hindi and a clown mask, hellbent to avenge his father's death. Despite all valiant efforts of law enforcement, he eludes the Chicago police, using his acrobatic circus skills to escape. Chicago Detective cop Victoria calls Mumbai ACP Jai Dixit (Abhishek Bachchan) and his colleague, Sub-Inspector Ali Akbar Fateh Khan (Uday Chopra), for help in solving the case.Jai baits Sahir into robbing again by making it known he is involved in the case and that the thief is an amateur. Gathering information from a news channel regarding the plan, Sahir poses as an informant for Jai and sneakily gathers intel on the bank while deceptively giving Jai a red herring. Sahir dupes Jai by informing him of the existence of Chup Chap Charlie, a magician in another circus whom he thinks has the motive and the skills to pull off the bank heists. Currently, Charlie is incognito and no one has ever seen him as he hides behind his mask. Eventually, Sahir robs the bank, but Jai and Ali pursue him. Jai, while hanging on a helicopter ladder, shoots Sahir in the left shoulder before he escapes once again.Sahir relaunches the Great Indian Circus and hires Aaliya Hussain as an acrobat. Sahir hosts a grand opening night premiere of The Great Indian Circus. With Aaliya's help, he performs a magic trick with him disappearing in one place and showing up someplace else. The show is a hit, but shortly afterwards, Sahir is detained by the police, suspecting he's the thief.Jai confronts Sahir and strip searches him but there is no sign of the bloody bullet wound anywhere on Sahir's body. Jai storms out after menacingly threatening to prosecute Sahir one day. Sahir retires to his dressing room, where it is then revealed that Sahir has an autistic twin brother, Samar assisting him with pulling off the magic tricks, stunts and also helps in planning the heists. It is also revealed that Samar was the one who sustained the wound. In a flashback, Sahir switched places with him halfway during the police chase and swapped out. Consequently, Jai and Ali are sent home immediately after being fired from the case by Anderson and the Chicago police for their incompetence, but once they are escorted to the airport with their luggage, Jai is encouraged by Ali to prove Sahir's guilt by going rogue.Jai finds out about Samar by sneakily going backstage posing as a janitor and spying on the twin brother from behind an elevator. Jai then begins plotting against Sahir. Samar, being autistic, is kept in seclusion. He's allowed outdoors once a week on Sundays. Jai disguises himself and befriends Samar by hanging out with him at the amusement park while undercover in various disguises, earning Samar's trust. Jai then instructs Anderson and the Chicago Police Department rehire him and Ali on the case to help bring the criminals in. Samar distances himself from his brother by frequently hanging out with Jai, compounded by Samar shyly falling for Aaliya, creating animosity between the brothers. A furious argument ensues when Samar secretly goes out on a date night with Aaliya behind Sahir's back after Samar replaces Sahir as the main act in the circus show. Enraged, Sahir berates Samar for getting sidetracked, asserting his brother to focus on the task at hand, resulting in Samar storming off to go out on a date with Aaliya and even ends up kissing her. Jai tries to exploit it, but Sahir finds out by eavesdropping on Samar at a nightclub gala party. He comes in disguise of Samar when Jai reveals his true self, telling him to surrender since he can give them justice. After Sahir reveals his cards as Samar, he ties Jai to the tracks of a roller coaster, leaving him behind to die. Ali arrives in time to save him from being crushed. Jai decides the only way to catch the brothers in is in the act the midst of a heist.Meanwhile, the brothers have forgiven each other and gear up for the ultimate heist to topple the corrupt bank once and for all. Sahir and Samar successfully pull off their final bank heist by disguising themselves as SWAT cops and escape on their motorcycles after detonating a bomb they had planted earlier in the bank, but find themselves cornered on the morning of next day at a dam on the outskirts of the city. Samar hesitates and refuses to flee when Aaliya shows up, begging him to stop. With no other option, Sahir unconditionally surrenders to Jai by giving him a disc containing information about the heists. Sahir begs Jai to spare Samar. Jai begrudgingly agrees, but immediately afterwards, Sahir jumps off the dam. Samar grabs Sahir's hand, refusing to let him go. Sahir demands Samar to release him by saying he can live happily ever after with Aaliya. But Samar declares that since they were both born together, they should also die together. Samar loses his grip, and the onlookers, police & Aaliya helplessly watch the 2 brothers fall to their death into the abyss while smiling at each otherThe movie ends with the Western Bank of Chicago permanently shuttering it's operations as a result of the heists, while Aaliya has taken over The Great Indian Circus. Sahir and Samar are shown performing together somewhere, implying they somehow survived.