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.

Meera (Diana Penty) is a shy and simple traditional girl who leaves her family in India to live in London with her new husband Kunal (Randeep Hooda). While at the London airport, she meets the shameless flirt Gautam "gutlu" (Saif Ali Khan), who hits on her and asks her out. Meera politely tells him that she is married and then leaves. Meera searches for her husband and finally finds him, but he is angry to see her and explains that he only married Meera for her money, telling her to stay away from him. This leaves Meera heartbroken and stranded in London with no place to stay.

While in the bathroom at a department store, Meera meets party girl Veronica (Deepika Padukone) who sees Meera weeping and decides to help her. Veronica takes Meera to her apartment and explains that her estranged father sends her a large amount through cheque every month, which helps Veronica enjoy the life of a rich socialite. One night, Veronica takes Meera to a nightclub, where they run into Gautam. At the club, Gautam and Veronica dance intimately and make out. The next morning, after an interview, Meera comes home to find Gautam on the couch. She learns that Gautam and Veronica slept together the previous night.

Soon, Gautam moves in with Veronica and Meera, continuing his "no strings attached" relationship with Veronica. Although Meera initially dislikes him, she eventually accepts him, and the three become best friends. Things get complicated when Gautam's mother (Dimple Kapadia) shows up, wanting to know if Gautam has found the girl he wants to marry. He lies to his mother and says that he is in a relationship with Meera because she is the "ideal Indian girl" who would meet his mother's approval. During this charade, Gautam and Meera end up falling in love. However, Meera is hesitant to admit it, because she does not want to hurt Veronica, who has fallen in love with Gautam and is trying to win the approval of his mother by becoming a proper Indian girl. Gautam sits the two girls down and explains to Veronica that even though she loves him, he is in love with Meera. Meera apologises to Veronica, but Veronica assures her that it is okay and insists that they all go to the club to celebrate.

However, at the club, a drunken Veronica breaks down, telling Gautam that she will do whatever he wants, and she tells Meera that no one has ever used her the way Meera did. The next morning, the three part ways. One night, Veronica is injured after being hit by a car. Gautam rushes her to hospital. Meera comes there with Kunal to make it look like she has gotten over Gautam.

Gautam moves back in with Veronica to care for her. Veronica realises that Gautam is no longer the flirtatious, fun-loving man with whom she fell in love and that he is that man only when he is with Meera. She sacrifices her love for Gautam realising she is not perfect for him, and she helps him locate Meera. They seek out Kunal, who tells them that Meera left him because she loved Gautam too much and that she has gone back to India. Gautam and Veronica travel to Delhi. Gautam proposes to Meera, and she accepts. Veronica and Meera became best friends again.

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.

Rajveer Singh (Saif Ali Khan) has an immense passion for stock car racing and dreams of making it big on the racecourse. After being discovered by his manager Harry (Jaaved Jaffrey), he meets Radhika Shekar Rai Banerjee (Rani Mukerji) and instantly falls for her. He joins Speeding Saddles, a failing race team, and transforms from Rajveer Singh to RV the race car driver. He wins his first race and keeps winning, making him quite wealthy.

What started as an innocent love blossoms into a serious relationship as months pass. Radhika is a great pianist, majoring in music at Columbia University, whereas Rajveer has no degree or any education background. His lack of education and planning earns the disapproval of Radhika's father, Subho Shekar Rai Banerjee (Victor Banerjee). Radhika leaves her father and marries RV. She forgets about her degree and takes on her job as a wealthy housewife: Radhika Shekar Rai Banerjee turns into Shona. Their family is complete with the birth of two beautiful children, Shanaya aka Princess (Angelina Idnani) and Pradeep aka Champ (Ali Haji). Luck follows RV and he is soon proclaimed the number one race car driver in the USA.

Tragedy strikes when RV is involved in an accident whilst racing and he is hospitalised for a few months. When he gets out, he heads straight to the track to race again but soon learns that he's scared of going fast because he doesn't want to crash and get hurt again. Every race he joins, he ends up in last place. His manager fires RV and finds someone else. RV tells Harry that he doesn't need him, he can find some other manager easily.

A year has gone by and neither RV nor Shonaa have jobs. They try their best to find work but no one will hire them because they don't have degrees. RV and Shonaa are unable to pay their loans and bills so everything they own in their house is sold. Princess and Champ worry that they're becoming poor; RV says they're actually on a reality show, Don't Worry, Be Happy. With about $2,000 left, RV and family leave their big house and find a less expensive one.

They move into a one-bedroom apartment, and the children become worried again. RV and Shonaa tell them this is all part of the game and the kids believe them. They still go to their favorite school while their parents try to find jobs.

A few days later, Shonaa gets a job as a piano player and RV becomes a taxi driver.

One night when RV and Shonaa start arguing, Princess overhears them and learns that they actually are in trouble with money. She then plans to save up the money she and Champ use for lunch. The kids don't eat, and Champ gets starved. He takes food from the garbage without his sister knowing and eats it outside of school on a bench. He keeps eating from the garbage while Princess keeps saving up money. Princess makes Champ promise not to tell their parents, knowing they'll get mad.

RV gets a customer who needs to get to the airport soon. He takes this chance as to test his racing skills. RV starts off doing great until he gets flashback on his accident. He then learns that he could probably never race again because of being scared of getting hurt.

Champ gets a piece of glass inside his stomach from eating something. RV, Shona, and Princess run to the hospital where Princess tells her parents the plan she made Champ follow. The doctor tell RV and Shonaa that they need $65,000. The couple has no idea how they are going to get the money and only have two days to get it. RV decides to enter a race for his son's sake. He meets his old nemesis and he starts remembering the flashbacks. But that doesn't stop him. He wins, while apparently killing his nemesis by pushing him off the track. In the end the family is living a happy and fun life.