Siddharth "Sid" Mehra (Ranbir Kapoor) is the carefree son of wealthy businessman Ram Mehra (Anupam Kher) and Sarita (Supriya Pathak) in Mumbai. Depicted as a spoiled slacker, Sid shows little concern for his plans after college, barely studying for tests and having no interest in working for his father. On the night after the final exams, he meets Aisha (Konkona Sen Sharma), an aspiring writer recently moved away from her hometown of Calcutta and a few years older than Sid. With the help of Sid, along with his friends Rishi (Namit Das) and Laxmi, Aisha finds a small apartment overlooking the city skyline. She also lands a job at Mumbai Beat (based on Time Out! Mumbai), a hip magazine run by editor-in-chief Kabir (Rahul Khanna), whom Aisha is attracted to.
After learning that he has failed the final exams (delaying his graduation for another year), Sid displaces his frustration onto Rishi, and later gets into a heated argument with his parents, ending with him moving out. Aisha allows Sid to temporarily stay at her apartment, but finds him disorganized and careless with her home. One night, Aisha loses her temper and yells at Sid for his inability to clean up after himself. The next morning, Sid confides in Aisha that he now realizes his constant dependence on Ram's wealth, a realization that persuades him to seek work. Aisha helps him land a role as a photography intern - photography having been a hobby of his since childhood - at Mumbai Beat.
The internship slowly motivates Sid to be more responsible and productive. He reconciles with Rishi when they meet again for the first time since their fight. Sid eventually gets hired full-time at Mumbai Beat and receives his first paycheck. He makes amends with his parents, and Ram invites Sid to return home. Aisha and Kabir start dating, but she quickly realizes that, despite her initial attraction to him, they have very little in common. Aisha then develops feelings for Sid, and on the day he packs his belongings to move back in with his family, she is furious to hear that he is leaving. Confused and hurt, unaware that Aisha has fallen in love with him, Sid makes his departure.
Back at home with Ram and Sarita, Sid receives the latest issue of Mumbai Beat. He reads Aisha's column, an article describing her adjustment to life in Mumbai and her love for an unnamed person. Realizing that it is about her feelings for him, Sid rushes through rainy weather to meet her at the same beach where they had gone the day they met. Sid expresses his love for her and the two embrace.
Why is Aisha furious to hear that Sid is moving?
in love with him