The movie starts with a kidnapping. The only son of a very successful and rich casino owner in Goa, Sonia [Isha Koppikar] goes missing. The toddler, is the apple of her eyes and she is devastated. To get her son back, she announces a reward of Rs. 25 lakhs to anyone who can bring him back.
Priya [Kareena Kapoor] and Raj [Shahid Kapoor] who don't know each other, accidentally spot the child and decide to bring the child back to Sonia in order to get the reward money which they plan to split between themselves. However, when they reach their destination they find her dead body there. They thereafter escape, but leave Priya's suitcase behind by mistake.
Akshaye Khanna is the police inspector assigned to the case, and soon discovers Raj and Priya's involvement on the night of the murder. They become chief suspects in the murder. However, subsequently many new angles to the case are unravelled with investigations.
The people involved in the case besides Raj and Priya, as suspects are two couples [Johny Lever-Tanaaz / Paresh Rawal-Payal Rohatgi], a playboy [Upen Patel], a drunkard [Raj Zutshi] and the domestic help [Dinyar Contractor, Roshan Tirandaaz]. Who's the murderer? Watch this Who - Dun - It to know.