Young Raj Malhotra (Akshay Kumar) lives with his elder brother, Rohit his sister-in-law Kiran, and a niece. After an accident fractures his leg, he is unable to walk for some time. Due to psychological reasons, he cannot walk even after the fracture heals. When the Malhotras move to Dehra Dun, Raj befriends their neighbour, young tomboy Kajal (Lara Dutta), as both share a common passion for aeroplanes. Kajal encourages Raj to walk, and he succeeds. Years later the two continue to be fast friends, and everyone expects them to marry soon. Raj secretly loves Kajal and is waiting for the right time to propose her. However, Kajal sees him only as her best friend. Raj is recruited by the Indian Air Force and goes for training for a year and a half. After his training gets over, he rushes to Kajal to propose her, only to find out that she has given her heart to a multimillionaire, Karan Singhania (Aman Verma). Raj tells Kajal that Karan is the best life partner for her, but does not reveal his true feelings. Kajal and Karan get married and during the reception party, Kajal comes to know about Raj’s feeling for her. Hurt by the fact that she did not see his feelings for her despite being Raj’s best friend, Kajal asks him to move on in his life as now she is a married woman. Thereafter the Malhotras move to Nainital, and Raj relocates to Cape Town for training.
During a visit to a club, Raj meets the vivacious and fun-loving Jiya (Priyanka Chopra). Jiya falls in love Raj due to his clean personality, but Raj, however is unable to take Kajal out of his mind. After completing his training, Raj goes back to India where he finds that Jiya had already arrived in his home as is living as a paying guest with Malhotras. Jiya makes several attempts to impress Raj, however, Raj still doesn’t fall for her. During Karwa-Chauth, Jiya performs rituals but, Raj gets angry and Jiya leaves the home. Raj’s family reveals that they had always loved Jiya and wanted Raj to marry her as Jiya had already told everything about her and Raj’s meeting in South Africa. Due to this, Raj decides to marry Jiya and move on with his life.
While visiting Jiya’s family, Raj learns that Kajal is Jiya’s sister-in-law. Also he comes face to face with the harsh truth that Kajal is a widow now after Karan’s death in a plane crash, in which Kajal survived. Kajal thinks that she is responsible for Karan’s death as she had asked Karan for a ride in a bad weather and also loses her mental balance and ends up in a hospital after attempting suicide. Raj helps recovers Kajal from the depression and enables her to come face to face with life again. Jiya gets angry about their increasing closeness and suggests her father for Kajal’s remarriage. At the engagement ceremony of Raj and Jiya, Kajal comes to know that her family has arranged her engagement also. Unhappy with the news, Raj asks Kajal not to marry Monty. However, Jiya reveals that Raj and Kajal have not forgotten about their past and they want their relationship to rekindle despite Raj and Jiya’s marriage. Angry Raj puts sindoor on Kajal’s head indicating he has now married Kajal and no one has the right to question their relationship. An emotional and heartbroken Jiya reveals that she wanted Raj to accept his feeling and love for Kajal in front of the world. The film ends with Jiya participating in Raj and Kajal’s marriage.