Karan [Saif Ali Khan] is a cartoonist and a self-styled ladies man. His daily comic, named "Hum Tum," explores the battle of stereo-typical behaviour. On a plane from Delhi to New York, he meets Rhea [Rani Mukerji], but she doesnt seem the to be a least bit interested in him. His feeble attempts at flirting go nowhere, but when they have a stopover in Amsterdam on their way to New York, she agrees to spend a few hours exploring the city with him. Karan quickly learns he has little in common with the feisty but proper Rhea, but he wont give up. He ends their contentious time together with an unwelcome kiss. Rhea is outraged, slaps him, and storms off, but Karan insists theyll meet again. After a couple months living in New York, he spots her in the park, and she causes a scene with his girlfriend,who is Rheas friend, this ends in the break-up between Karan and his current girlfriend. Now three years later, when Karan is helping his mother plan a wedding that turns out to be Rheas. Rhea is marrying Sameer [Abhishek Bachchan]. They bicker again, but this time, they part on good terms. Years later in Paris [although the scenes were clearly also shot in Amsterdam, this part of the film is supposedly located in Paris], Karan is visiting his father [Rishi Kapoor], when he runs into Rhea again. He learns from Rheas mother [Kirron Kher] that Sameer has died in a car accident, and he sets out to help her reclaim her positive outlook on life. Karan goes back to Mumbai, and three months later, Rhea and her mother visit. Sensing that she needs to be with a straight-laced, "boring guy", he conspires with Rheas mother to fix her up with his shy best friend, Mihir [Jimmy Shergill]. But eventually Mihir falls in love with a friend of Karans, Diana [Isha Koppikar] and they get engaged. On the engagement night Rhea learns from drunk Diana about the conspiracy. Mihir makes Rhea realize hers and Karans love for each other. That night Rhea and Karan consummate their relation. Karan finds it a mistake and asks Rhea to marry him as he feels she could never fall in love with a guy like him. Rhea gets upset as she realizes she loves him but tells Karan that they should not commit one more mistake. Rhea leaves him as she misinterprets his confused feelings as guilt [about having made love] rather than love for her. Karan realises his mistake, and goes out to find her. One year later, Karan and Rhea reunite again. Karan admits his love for her, and they get married and have a baby girl.

2005 national film awards

= * National Film Award for Best Actor - Saif Ali Khan

2005 filmfare awards

= * Best Director - Kunal Kohli * Best Actress - Rani Mukerji * Best Comedian - Saif Ali Khan * Best Female Playback - Alka Yagnik * Best Scene