Trama

A novel look at the eternal battle of the sexes and the trials and tribulations of Karan and Rhea and their attempts to understand each other.

Life is not always like the movies. Love isn't always at first sight. Very often, a relationship develops slowly and it takes many years between "boy meets girl" and "boy gets girl". Hum Tum is a refreshing look at the eternal battle of the sexes as it follows the lives of Karan (Saif Ali Khan) and Rhea (Rani Mukerji). Karan is a cartoonist and his character "Hum" and "Tum" reflect his perspective on the strange love-hate relationship between men and women. Rhea is sensitive, well bred and self-confident. She can give as good as she gets and is not afraid of standing up to men. Initially, the two have very little in common. But, as life would have it, their paths keep crossing and, over the course of a decade, their relationship evolves, from hate to mutual respect, friendship and finally - In a cinematic universe that offers simplistic scenarios to the complex relationship between men and women. Hum Tum is a novel look at the trials and tribulations of "every man" and "every woman" and their attempts to understand one another.—Official Source

Karan has recently published a book on the topic male/female behavior, which has turned out to be a best seller. He is asked about the topic of love, and he says that he has only loved once, but the love came into his life many times over the years.

The story shifts to 9 years ago. Karan Kapoor (Saif Ali Khan) is a cartoonist and a self-styled ladies' man. His daily comic, named "Hum Tum," explores the battle of stereo-typical name/female behavior. On a plane from Delhi to New York, he meets Rhea Prakash (Rani Mukerji), but she doesn't seem the to be a least bit interested in him. Rhea is super organized and independent, while Karan is a bit of a sloth and self-centered.

His feeble attempts at flirting go nowhere (he guesses that Rhea drinks tea, when she drinks coffee), 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 won't give up. Karan smokes and Rhea hates smoking. Rhea loves museums and Karan hates them. Karan likes ogling at women, and Rhea is disgusted by that. Karan says that all men want only sex from women, and they will any lie to get it. Men also exaggerate.

He ends their contentious time together with an unwelcome kiss. Rhea is outraged, slaps him, and storms off, but Karan insists they'll meet again. Rhea says that Karan misinterpreted her going out with him in Amsterdam to believe that she was interested in him. Rhea says that Karan has no respect for women. After a couple months living in New York, he spots her in the park, and she causes a scene with his girlfriend Shalini Gupta (Shenaz Treasurywala), who is Rhea's friend from her school days. Rhea reveals to Shalini that Karan kissed her in Amsterdam while he was still dating Shalini. This ends in the break-up between Karan and his current girlfriend.

Now three years later, when Karan is helping his mother Anjali (Rati Agnihotri) plan a wedding for a client, that turns out to be Rhea's. Rhea is marrying Sameer Khanna (Abhishek Bachchan). Sameer and Rhea used to study together in college, and eventually proposed to her. Karan and Rhea bicker again about the reality of true love (where Karan argues that there is no such thing), but this time, they part on good terms.

Years later in Paris, Karan is visiting his father Arjun (Rishi Kapoor), when he runs into Rhea again. Rhea runs a boutique in Paris. Arjun is a fashion photographer and has been travelling the world for the last 8 years. Due to this, Arjun has never been home with Anjali for that duration. Karan learns from Rhea's mother Parminder "Bobby" Prakash (Kirron Kher) that Sameer has died in a car accident, and he sets out to help her reclaim her positive outlook on life. Karan invites Rhea for lunch, and Bobby encourages her to go as she only ever spends time in the house or at her boutique. Karan also brings Arjun to lunch with Bobby and Rhea. Bobby tells Karan that she wants to get Rhea remarried. Arjun opens up about his distance from Anjali to Rhea and this hurts Karan, as Arjun never had this conversation with Karan. Later, he thanks Rhea since Karan was never able to have this conversation with his father by himself. Rhea can see that Karan has really matured.

Karan goes back to Mumbai, and three months later, Rhea and her mother visit. Sensing that she needs to be with a strait-laced, "boring guy", he conspires with Rhea's mother to fix her up with his shy best friend, Mihir Vora (Jimmy Shergill).

But eventually Mihir falls in love with a friend of Karan's, Diana (Isha Koppikar) and they get engaged. On the engagement night Rhea learns from drunk Diana about the conspiracy. Rhea is livid at Karan for interfering with her life. Mihir makes Rhea realize hers and Karan's 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 he took advantage of her, and that marriage will rectify the mistake.

Rhea becomes upset, as she did not consider their actions a mistake; she realizes she loves him but tells Karan that they should not commit one more mistake by marrying for the wrong reasons.

Rhea leaves him as since Karan projects his confused feelings as guilt (about having made love) rather than love for her. Arjun returns from Paris and tells Karan that he is making the same mistake that Arjun made with Anjali, by not recognizing her love. Karan realizes 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.