A robbery takes place and European printing plates are stolen. Ranvir Singh (Saif Ali Khan) sees this news on TV and decides to take advantage of this to get revenge for a past matter. Ranveer cons Vikram Thapar (Rajesh Khattar) by pretending to have stolen the Euro printing plates, and his plan is successful. He cons Vikram so badly that he is divested of the five casinos that he owns in Istanbul, Turkey.

This con is revealed to be a plan that Ranveer made a week earlier with ex-street fighter and current casino mogul Armaan Malik (John Abraham). Ranveer was introduced to Armaan by his friend Robert "RD" D'Costa (Anil Kapoor) and his dimwitted assistant Cherry (Ameesha Patel). After the con, Ranveer gives Armaan ownership of Thapar's five casinos in exchange for 10% of the money. With this deal, Ranveer and Armaan become friends. Ranveer also romances Armaan's half-sister Alina (Deepika Padukone), who is his 50% business partner in all his ventures and spent a night with him to start their partnership.

At a party hosted by Armaan and Alina, Ranveer meets Armaan's girlfriend Omisha (Jacqueline Fernandez) and sees a picture of his deceased wife Sonia (Bipasha Basu) in her wallet. He charms her through matches of archery and fencing where he cuts her dresses without her knowledge and walks away without watching her without dress. Ranveer then tells Armaan of a deal that will get them endless money. Armaan agrees to the plan.

Later, Ranveer reveals to RD that he is not planning to make Armaan rich, but he is actually planning to con Armaan so badly that he will lose all his money and be forced to become a beggar on the streets. This is part of Ranveer's plan to avenge Armaan's killing of Sonia. He vows that until Armaan is ruined, he will not do Sonia's final rites. Ranveer then establishes contact with Omisha, who tells him that she is Sonia's sister Tanya and she too wants revenge. Omisha agrees to help Ranvir in his plan. However, right after Ranveer leaves, Armaan shows up at Omisha's apartment, where it is revealed that she is not actually Sonia's sister, but she is actually working for Armaan. Ranveer, however, does not know this and still believes that she is Sonia's sister.

After this, Ranveer shows RD and Cherry that his plan is to steal the Shroud of Turin. Ranveer will steal the Shroud himself, but will tell Armaan that he is getting someone else to do it. That person will ask for 15 billion Euros from Armaan, which Ranveer will secretly take. After that, he will get away with the Shroud and all of Armaan's money. RD is afraid of Armaan and therefore betrays Ranveer. RD tells Armaan all of Ranveer's plan. Armaan then tells RD to give Ranveer whatever help he needs, but RD will still be on Armaan's side.

Ranveer and Alina get closer and start dating. On one such date, Armaan informs them that there is a bomb planted under Alina's car. Ranveer somehow manages to get rid of the bomb and Armaan tells them that Thapar must have planted it to get even for the five casinos he was conned of.

Armaan then introduces Ranveer to the Mafia Godfather Anza. After Ranveer is out of sight, Armaan asks Anza for the 15 billion Euros to give for the Shroud of Turin theft. Anza says that he will give Armaan the money only if he wins a fight against Anza's prize fighter Typhoon. Ranveer was eavesdropping on this conversation the whole time, and when he turns around, he sees Alina standing there. Alina reveals to Ranveer that RD is actually on Armaan's side. She then reveals that Armaan actually wants to kill her and he was the one that planted the bomb in her car. But when he realised Ranveer was in the car, he warned them about the bomb and thus saved them. Armaan only wants Ranveer alive to keep the plan going. Alina takes Ranveer's side in the "race to the finish."

While Ranveer steals the Shroud of Turin with RD and Cherry, Armaan fights against Typhoon and wins. After the theft, Ranveer leaves the Shroud in a luggage locker at the airport and keeps the key on his necklace. Afterwards, RD and Cherry hook up at a nearby beach. Ranveer tells Omisha where the real Shroud is, and gives her a fake Shroud to give to the fake thief. Omisha tells Armaan about Ranveer's entire plan, and Armaan tells her to do exactly what Ranveer says.

At the ruins of Antalya, Ranveer's fake thief Eric meets up with Ranveer, Armaan, Alina, RD, and Cherry. As per Ranveer's plan, Eric gives Armaan the fake Shroud. He takes 15 billion euros from Armaan and drives away with Omisha hiding in his car. Eric gives Omisha the money and leaves. Back at the ruins, the remaining five celebrate the end of the deal with some champagne. After Ranveer drinks his glass clean, Armaan reveals that Alina mixed poison in Ranveer's glass. As Ranveer slowly dies, Armaan reveals that thanks to RD he knew Ranveer's plan the whole time and he was controlling the race the entire time. Alina reveals that she was never on his side because of her blood relationship with Armaan. Omisha drives back with the money and reveals to Ranveer that she was also on Armaan's side and she is not Sonia's sister. After Ranveer dies, RD and Cherry leave after getting 10% of the money from Armaan. Alina leaves to get the private jet ready, while Armaan and Omisha retrieve the real Shroud from Ranveer's luggage locker.

Armaan, Omisha, and Alina leave in their private jet. While in the jet, Armaan points his gun at Alina, revealing that all along he was planning to kill her and take her money. Suddenly, Ranveer crashes through the wall and reveals that Alina never poisoned his drink. Alina tells Armaan that she was on Ranveer's side ever since Armaan planted the bomb in her car. Ranveer reveals that RD never betrayed him, and that he himself told RD to inform Armaan of the real plan. This was to make Armaan think he was ahead of Ranveer. Ranveer then reveals that he had seen a picture of Sonia's sister before he even met Omisha. Therefore, he knew all along that Omisha was not Sonia's sister and was on Armaan's side. This leads to a fight between Ranveer and Armaan on the plane, while Alina and Omisha watch fearfully. The plane begins to spiral out of control after Armaan breaks a window. During the fight, Armaan reveals that before Sonia was with Ranveer, she was dating Armaan, but she lied to him and stole his money, which is why he had her killed. He then shoots the pilot and all but one parachute. As the plane is about to crash, Armaan and Omisha take the parachute escape with the real Shroud and the money. Ranveer and Alina then also escape the plane, but with nothing.

When Armaan and Omisha give the Shroud to Godfather Anza, it is inspected and revealed to be fake. Then, they give the money to Godfather Anza, but that is also fake. As a punishment, Anza takes everything from Armaan: his casinos, his money, his house, his cars, his yachts, and even Omisha. As Armaan leaves, he vows to get revenge on Ranveer claiming that after one race finishes, another one begins right from there.

Ranveer lays flowers on Sonia's grave as Alina watches on. They then meet up with RD and Cherry, and Ranveer gives RD 10% of the money they made from ruining Armaan. There, Ranveer reveals that the Shroud was never even stolen from the Church of Turin because it was too holy to be sold in the underworld market. RD then tells Alina that he never trusted her even though Ranveer trusted her fully. Ranveer reveals how after everyone left the ruins of Antalya, Alina came back to take Ranveer to the jet. Then, they reveal how Alina switched the real money with the fake money while Ranveer and Armaan were fighting in the jet. RD then says that he does not want to risk his life again and makes Ranveer promise to never meet him again. Ranveer shakes on the promise but then warns RD that promises are made to be broken. RD and Cherry then leave in one small aircraft, while Ranveer and Alina leave in another.

Uday (Nana Patekar), a criminal don, takes it upon himself to get his kindhearted sister, Sanjana (Katrina Kaif) married, but he is unsuccessful since no one wants to be associated with a crime family. Dr. Ghunghroo (Paresh Rawal) has also been trying to get his nephew, Rajiv (Akshay Kumar), married but due to his condition—the alliance must be with a purely decent family—he is also unsuccessful.

When Rajiv jumps into a burning building to save Sanjana, he is smitten by her. Uday and Majnu (Anil Kapoor), Uday's friend gangster hatch a plan for an alliance with Dr. Ghunghroo. The plan works and Dr. Ghunghroo confirms the alliance, thinking that Uday is a very decent man. But when he is later told that Uday and Majnu are mobsters, he quickly takes his family and flees to Sun City, South Africa to escape. However, Majnu and Sanjana have come to Sun City as well. Rajiv meets Sanjana again and the two fall in love.

Dr. Ghunghroo reconciles with Uday and Majnu and finally agrees to the alliance. Uday and Majnu invite a powerful don of the underworld, RDX (Feroz Khan) to the engagement. At the party, a girl named Ishika (Malika Sherawat) arrives, claiming to be Rajiv's childhood betrothed. Ishika is actually the sister-in-law of Dr.Ghunghroo that Dr. Ghunghroo asked to come and try to break off the engagement. Ishika manages to do so, leaving Rajiv and Sanjana heartbroken. Dr. Ghunghroo reveals that he did this for Rajiv's mother, who had married into a crime family and was harassed and tortured, thus telling Dr. Ghunghroo to raise Rajiv away from crime when he was born. Dr. Ghunghroo decides he will agree to the marriage only if Uday and Majnu give up their life of crime. Rajiv and Sanjana do this by reawakening Uday's love for acting and encouraging Majnu to pursue his love for painting. With these things keeping them busy, Uday and Majnu have no time for crime any more.

Rajiv's actions anger RDX's son, Lucky, who attempts to shoot Rajiv. Sanjana gets hold of the gun and fires a shot that hits Lucky, causing him to go unconscious. RDX is informed of his son's death and comes to attend the cremation. However Lucky, who is still alive, escapes, trying to show his father that he's actually alive. RDX sets the pile of wood on fire, believing he is cremating his son's body. However Lucky, who had been hiding under the wood, jumps out upon realising the wood is on fire, and the truth is revealed to RDX. Rajiv, Ghunghroo, his wife, Ishika, Uday, Majnu and Sanjana are captured by RDX and brought to a cabin set next to a cliff. The frightened group is forced to play "Hot Potato" with a globe—but the one who ends up with the globe must jump off the cliff. When Rajiv refuses to pass the globe to Sanjana, Lucky angrily yanks it out of his hands, just as the music stops. Now that his son has the globe, RDX figures the only way he can maintain his image is by killing everyone. Before he can, several government brokers sneak up and cut the footings of the cabin, causing the house to start falling over the cliff, with everyone trapped inside. However, the cabin is suspended by only one column. Hilarious chaos ensues as the group tries to balance the cabin together and keep it from falling off the cliff. Rajiv finds a rope and the group uses it to get back onto stable ground. But to everyone's shock, the floor broke and Lucky was hanging on the edge of the cabin. While Rajiv is trying to rescue him, Sanjana reveal the truth to everyone that she was the one who shot Lucky, but Rajiv blamed himself so that Sanjana won't get in trouble. After Rajiv rescued Lucky, the cabin he is standing on fell off a cliff. Sanjana kept crying for him thinking he is dead. However, Rajiv survived the event and is reunited with Sanjana and his family. Lucky and RDX are grateful to Rajiv for saving their lives and RDX gives up his life of crime, allowing Rajiv and Sanjana to finally get married.

A voice-over by RD (Anil Kapoor) introduces the four main characters: Ranvir Singh (Saif Ali Khan) who runs a successful business he inherited from his father. His younger brother Rajiv Singh (Akshaye Khanna) who mooches off of Ranvir and is an alcoholic. Ranvir is dating an upcoming model Sonia (Bipasha Basu), while his personal assistant Sophia (Katrina Kaif) appears to be secretly in love with him. Ranvir is also involved in an intense competition with a rival horse-owner Kabir (Dilip Tahil). The film opens with a murder plot involving a car accident which Ranvir narrowly survives. When Ranvir loses money in a race because his jockey had been bribed by Kabir, Ranvir plants a bomb in the jockey's car and kills him, showing Ranvir to be a ruthless businessman.

In a drunken stupor, Rajiv confesses to Ranvir that he likes Sonia and that he would quit drinking if he could spend his life with a woman like her. Ranvir immediately stops dating Sonia so that Rajiv can have her. Rajiv and Sonia begin dating and appear happy until, in a twist, Rajiv reveals he knows of Sonia's shady past and has a plan to use Sonia to his advantage. Rajiv reveals that his father had secured identical life-insurance policies for huge sums on each of the sons. He explains that he wants to kill Ranvir in what would appear to be an accident and inherit $100 million in insurance payments and wants Sonia to play along. Sonia agrees to help in exchange for $20 million. They pretend to get married and Rajiv ignores Sonia in this fake-marriage while continuing to play an alcoholic. As per his instructions, Sonia seduces Ranvir who confesses he loved her all along. Rajiv reveals the rest of his plan: to threaten to commit suicide in response to Sonia and Ranvir's affair by leaping off a tall building, have Ranvir appear on the terrace, and get Sonia to push Ranvir off. However, it turns out Ranvir was aware of the plan all along as Sonia, who had apparently fallen in love with Ranvir, had been keeping him updated.

Things go according to plan but Sonia double-crosses Ranvir and pushes him off, saying she loved him, but the money was more important. Inspector RD appears at this point to investigate the death, accompanied by his idiotic assistant Mini (Sameera Reddy). Upon his arrival, he immediately suspects foul-play in the death. During his investigation, Ranvir's assistant Sophia reveals that she was married to Ranvir and produces a legitimate marriage certificate. Sonia is shocked that their plan has been thwarted as Sophia is now the heir to the insurance money. In another twist, Sophia was in on the plan all along and is secretly dating Rajiv. Rajiv plans to bump off Sonia after he and Sophia get the insurance money. However, RD figures out during his investigation that Sophia and Rajiv had faked her marriage with Ranvir and that he had been tricked into signing the marriage certificate. RD confronts Rajiv about this and agrees to remain silent about it in exchange for $25 million.

Rajiv hires the same hitman who had attempted to murder Ranvir at the beginning to kill Sonia, revealing that he had been behind the first murder attempt, too. Just as the hitman is about to kill Sonia, Ranvir reappears and rescues her. Ranvir then confronts Rajiv and explains that he had overheard Rajiv discussing the failed murder attempt with the hitman and had been playing along the whole time so he could get the insurance money from his own fake-death and the insurance money from killing Rajiv. He allows Rajiv one last chance to win by agreeing to a car race. Ranvir shows up to the race in a sports car, whilst Rajiv doesn't. When Rajiv protests, he switches cars with Ranvir. This turns out to be a trick as Rajiv had tampered with the brakes on his own car. Ranvir, in turns, lies to Rajiv, claiming he had planted a bomb in his car, similar to the one that killed the jockey, and that it would be detonated if Rajiv ever slowed down below 100 mp/h. This deceives Rajiv into crashing into a petroleum tank, killing him and Sophia, who had been riding with him. Ranvir narrowly escapes death himself. Ranvir then says that there was no bomb in the car, and that Rajiv had "killed himself".

In the end, Ranvir collects the insurance money from Rajiv and Sophia's death, along with the money from his own fake-death. Upon fleeing the city, he is stopped by Inspector RD, who had been in on the plan, too, and had helped Ranvir fake his death and get the insurance money. Inspector RD takes his another $25 million, only to find a bomb in the bag along with the money. The bomb does not detonate, and Ranvir reveals that it was a mere precaution to see if RD would try to betray him and take all the money. Ranvir rewards RD for his relative honesty by allowing him to live, and the two drive off.