Naina, played by Preity Zinta lives with her widowed mother Jennifer, played by Jaya Bachchan in New York. She also lives with her biological sister and adopted sister as well as paternal grandmother. Her grandmother and mother don’t get along as the former blames her mother for her son’s death. This creates a lot of tension in the house where her grandmother doesn’t treat her adopted daughter well as she is her son’s illegitimate child. Naina has two close friends Rohit, played by Saif Ali Khan and Sweetu. Naina and Rohit study together but he is a womanizer and Naina makes fun of him for that.
Meanwhile a new neighbor named Aman comes to live near Naina’s house. He is friendly and befriends all family members of Naina except her. She is hostile towards him but eventually begins to like him. Meanwhile Rohit starts falling in love with Naina but is unable to tell her. Naina realizes that she is in love with Aman and goes to his house to tell him but is shocked to find out that he is already married. Later it is revealed that Aman has a heart problem and will not live very long, thus he fakes his marriage to Naina even though he too loves her.
Aman gets Rohit and Naina close to each other. Meanwhile when Aman is on his death bed he promises Rohit that he will be with Naina in his next life. The movie is directed by Nikkhil Advani and produced by Yash Johar and Karan Johar. The music is composed by Shankar-Ehsaan-Loy.