Chandramohan Manohar Sharma, better known as Charlie (Shah Rukh Khan), is a street fighter who has been yearning for revenge from Charan Grover (Jackie Shroff) for 8 years. Because of him, his father, Manohar Sharma (Anupam Kher) was labeled as a thief because Charan had conned him into stealing the Mughal Diamonds & Manohar was sent to jail. Charlie finds out in the media that some world famous diamonds will reach the Atlantis Palm hotel on Christmas Eve & will be kept in Grover's Shalimar vault (that was built by Manohar) for 1 night only. Charlie wants to steal the same diamonds and frame Grover for the theft. To accomplish this, he must assemble a dynamic team.First in his team is Jagmohan Prakash, or Jag (Sonu Sood) who has a hearing deficiency and gets furious when anyone abuses his mother. Second on his team is Tehntroman Irani, or Tammy, (Boman Irani) who is an overweight jogger and suffers from epileptic fits. Tammy used to be a test engineer in Manohar's factory & is an expert safe cracker. Tammy also wanted revenge on Grover for destroying Manohar's life. It is also revealed that Tammy and Manohar were best friends. Third on the team is Rohan Singh (Vivaan Shah), a young hacker who will be able to hack Shalimar's computerized system. He is also Jag's nephew. After thoroughly researching about the vault, the team finds the main vault comprises a bio-metric lock (fingerprint lock). The problem is that only one person can access the vault at any time: Vicky Grover, Charan's son. So they enlist the aid of a lookalike, Nandu (Nandan) Bhide (Abhishek Bachchan). Nandu agrees to the job as he needs the money for his mum's tumor surgery. Charlie describe his team as Ek all time Bewda (Nandu), Ek Sanki Jadeya (Tammy), Ek Bhari Banduk (Jag), Ek Badmaash Bachcha (Rohan).The team heads to a warehouse which was originally their workshop for a rehearsal. It is revealed that Tammy was immensely in love with the Shalimar vault and he only knew the sole combination to the vault. The real Shalimar vault has a laser shield in front of the vault whose code combination is changed everyday. The team finds out a weakness that the Shalimar safe is in the Altantis hotel underground which is connected through a sewer system which is further connected to room 9C. But the room is only open for any one team from the World Dance Championship (WDC), a dancing competition, which will be held at the Atlantis hotel on Christmas eve, the same time the diamonds are held in the Shalimar vault in the Atlantis hotel. Unfortunately, none of them can dance.The real story is eventually revealed: Manohar was an engineer in vaults. He met Charan Grover, who was a dealer in African diamonds who gave him a contract to build an impenetrable vault. After the vault was completed. Charan drugged Manohar and conned him. The vault was newly installed in Grover's house by Manohar & diamonds worth 100 Crores were deposited inside. Grover drugged Manohar & used his fingerprints to steal the diamonds & blame the theft on Manohar (as his fingerprints were still on the vault's bio-metric security system) desperate to win the competition, they employ the help of Mohini Joshi (Deepika Padukone), who is a Marathi bar dancer who trains them to dance. Mohini needs the money to open her own dance school & is a sucker for English speaking folks, which makes her work with Charlie. During this time, Charlie and Mohini fall in love.They manage to qualify in the first round (by blackmailing the judges with evidence of their secret homosexual relationship) and eventually win the competition to represent Team India in the WDC (by having Rohan hack the machine that tallies the votes). Many people (including and especially Indians) despise them for their lack of dancing skill, but Charlie and his team (minus the oblivious Mohini) are all only concerned with the heist.The other competitors are especially hostile towards Team India, especially Grover as he considers India as a team of losers. During the first round, they are pitted against Team Korea, however their performance is halted when Charlie saves a falling child of the rival team, instantly gaining respect and admiration from the audience the world over as well as the other teams (including the grateful Team Korea). The team eventually find out that the diamonds will arrive on New Year's Eve instead of Christmas which impedes the heist. Though Team Korea secure the last position in the semifinals, the judges, moved by Charlie's saving of Korea's dancer and their spirit, decide that Team Diamonds will compete in the finals as a wild card addition. Over the course of the weeks leading up to the finals, the members of Team India become beloved celebrities in the eyes of the public.Mohini ends up hearing the whole story as to why they wanted revenge, angrily confronting Charlie and his false motivations of the competition. Charlie reveals a shocking secret that Manohar is not in jail but is actually dead, as he committed suicide. He kept this a secret from the other members in order to keep from demoralizing them. However, the team confides that this only makes their determination to avenge Manohar even stronger. Mohini reluctantly joins the team and helps them for the heist. The night of the final round, the heist is set in motion. Mohini lures Vicky into an elevator, allowing a disguised Nandu and Jag to sedate him temporarily while Nandu takes his place. For the thumb print, Jag paints his thumb, removes it and places on Vicky's thumb matching the print. While Tammy cracks the vault combination, he suffers an epileptic fit, however they open in time.Everything seems to go very well until Charlie and Tammy find another safe inside made of glass which houses the diamonds and Vicky ends up waking up.Tammy realizes that Manohar built this safe but Charlie manages to crack the password (which is "Charlie"). After stealing the diamonds (and covering all of their tracks), the team boards a nearby boat, but Mohini doesn't want to come as she feels dedicated to protecting India's honor with the competition. Rohan eventually resolves to join her as well, leading to a fight among the other members over what they should do next.Grover is horrified to find the diamonds stolen (with "Vicky's" opening of the door to the safe's room incriminating both him and Grover), but he soon pinpoints Team India as the thieves. As he watches Mohini perform, Jag, Tammy, Nandu and Rohan join in. During their performance, Charlie makes his unannounced appearance and eventually helps the team win the competition.With any and all suspicions removed from the members of Team India, Grover and Vicky are arrested, Charlie revealing himself and Manohar's son just as they are both dragged out of the hotel by police. Team India reach the airport and manages to bypass security (Charlie camouflaged the diamonds as ice cubes in his cool drink), but the security guard disposes it. But during the flight Charlie reveals that he switched the fake diamonds on the trophy with real diamonds and the diamonds in the drink were fake so the diamonds on the trophy are the real Shalimar Diamonds. The film ends with Mohini opening a dance school. Charlie proposes to her by giving a ring made of one of the diamonds.