The film opens with Kabir (Abhay Deol) proposing to Natasha (Kalki Koechlin). Their families meet at the engagement party where Natasha learns that Kabir is planning a three-week bachelor road trip to Spain with his school friends Imran (Farhan Akhtar) and Arjun (Hrithik Roshan). Kabir explains that the three have a long-standing pact, and that during the road trip, each of them will have to pick an adventure sport which all three will try together. Initially, Arjun is reluctant to take trip as he does not want to lose his pay for missing work. It is later revealed that Arjun’s former girlfriend left him due to his workaholism and his obsession with money. Imran has an additional personal agenda on the trip, to find his biological father Salman Habib (Naseeruddin Shah), an artist in Spain.
They fly to Spain separately, where they plan to visit Costa Brava, Seville, and Pamplona. On the way to Costa Brava, Imran and Kabir find it annoying that Arjun works even during the trip. Imran nonchalantly throws Arjun’s mobile phone out of their car while he is in the middle of an official call. This leads to a heated argument. Arjun, in a fit of rage, accuses Imran of having an affair, four years prior, with Arjun’s previous girlfriend Sonali (a topic which was very sensitive both to Arjun and Imraan). After being pacified by Kabir and reaching their destination, they meet an Anglo Indian named Laila (Katrina Kaif) on a beach. Imran flirts with her and makes Arjun jealous. Kabir reveals that he has chosen deep sea diving as their first sport, and they later find that Laila is their diving instructor. Arjun, who cannot swim and is aquaphobic, receives assistance from Laila. She helps him overcome his fears and finish the sport successfully. Upon a request by Laila, they attend the La Tomatina festival with her in Buñol and meet Nuria (Ariadna Cabrol), who falls in love with Imraan. Meanwhile, Natasha becomes suspicious of Kabir’s involvement with Laila when she sees them via webcam and crashes his bachelor party trip, much to Kabir’s discomfort in front of his friends. Imran spends time with Nuria, and Arjun with Laila. After the boys leave, Laila realises she has fallen in love with Arjun and chases them on a bike, not wanting to regret their partition if they do not meet in future. She and Arjun express their feelings for each other with a passionate kiss.