Chandramohan Manohar Sharma, affectionately known as Charlie (Shah Rukh Khan), is a street fighter consumed by a desire for revenge against Charan Grover (Jackie Shroff), who has wronged his family for eight long years. This turmoil began when Charan duped Charlie's father, Manohar Sharma (Anupam Kher), into stealing the Mughal Diamonds, leading to Manohar's unjust imprisonment as a thief. In a twist of fate, Charlie discovers through the media that a quantity of world-famous diamonds is set to arrive at the Atlantis Palm hotel on Christmas Eve, where they will be secured in Grover's Shalimar vault (constructed by Manohar) for just one night. Charlie devises a plan to steal the diamonds and frame Grover for the crime, but he'll need to gather a team to execute this elaborate heist.
Introducing his first ally, Jagmohan Prakash, lovingly referred to as Jag (Sonu Sood), who struggles with a hearing impairment and possesses a fierce temper when it comes to insults directed at his mother. Next up is Tehntroman Irani, or Tammy (Boman Irani), a fun-loving, overweight jogger who deals with epilepsy and shares a profound grudge against Grover for the havoc he caused in Manohar's life. Tammy’s connection to Manohar runs deep, having been his closest friend. The third member is Rohan Singh (Vivaan Shah), a tech-savvy young hacker and Jag's nephew, tasked with infiltrating the vault's computerized security system.
Upon delving into the vault's security details, they discover that it features a biometric lock and can only be accessed by Vicky Grover, Charan's son. To bypass this hurdle, they enlist the help of Nandu (Abhishek Bachchan), a lookalike who desperately needs the money for his mother's surgery. Charlie humorously introduces his crew as: "Ek all time Bewda" (Nandu), "Ek Sanki Jadeya" (Tammy), "Ek Bhari Banduk" (Jag), and "Ek Badmaash Bachcha" (Rohan).
The team gathers in a former workshop, now a rehearsal space, to prepare for the heist. Here it’s revealed that Tammy alone knows the secret combination to the vault, which houses a laser shield that alters its code each day. They discover a crucial weakness: the vault is situated in the Atlantis hotel’s underground, linked through a sewer system to room 9C. But this is a problem, as room access is limited to competitors in the World Dance Championship (WDC), set for the same evening the diamonds are stored. None of the team members, however, possess any dancing prowess.
As their plan unfolds, the real twist becomes evident: Manohar, a skilled vault engineer, had constructed a vault for Grover, who subsequently betrayed him. After drugging Manohar and using his fingerprints to steal the diamonds, Grover framed him for the theft. To master the dance necessary for the competition, they seek the expertise of Mohini Joshi (Deepika Padukone), a talented Marathi bar dancer who yearns for the funds to launch her own dance academy. As they train together, romance blossoms between Charlie and Mohini.
Against all odds, the team secures a place in the WDC's next stage by blackmailing the judges with sensitive information. Public opinion may sway against them due to their inadequate dancing skills, but their sights remain firmly set on the diamonds instead of the competition itself. As tension mounts among competitors, especially from Grover, Charlie's bravery shines through when he saves a child from a rival team, which earns him worldwide admiration.
But complications arise when they learn the diamonds are now slated to arrive on New Year's Eve, complicating their heist. Despite Team Korea finishing last, the judges, moved by Charlie's heroic act, grant Team India a wild card entry into the finals. As they bask in newfound fame, Mohini learns the heartbreaking truth of Charlie's motives: Manohar had passed away, a casualty of his despair in prison, which amplifies the urgency of their revenge.
On the night of the finals, the heist commences. Mohini courageously distracts Vicky while Nandu and Jag render him unconscious, allowing Nandu to infiltrate the vault. The team faces numerous challenges, including Tammy’s unexpected epileptic fit, which nearly derails their efforts, but they soon access the coveted diamonds. Just as triumph appears within reach, they encounter an unexpected glass safe inside the vault.
As the plan draws dangerously close to unraveling, a hurried escape ensues amidst chaotic performances, with Charlie stepping onto the stage at a pivotal moment, ultimately leading Team India to victory. Their triumph clears them of suspicion while Grover and Vicky face justice. With a clever switch of diamonds, Charlie manages a stunning stroke of luck, leaving the real Shalimar Diamonds concealed in plain sight disguised as a trophy.
In a heartwarming conclusion, Mohini opens her dance school while Charlie seizes a beautiful moment to propose, presenting her with an engagement ring crafted from one of the diamonds they fought so hard to reclaim.
