Love blossoms between a Delhi college professor, Avantika (Kareena) and her newly joined colleague, Ehsaan Khan (Saif). But as she receives a call to join back her University in New York, Ehsaan proposes marriage. While her father initially disapproves of the match because of Ehsaan being a Muslim, he finally gives his nod impressed by Ehsaan’s approach. The couple goes to New York and finds a house in an Indian neighbourhood. But soon Avantika realizes her own husband is a major part of the terrorist sleeper cell operating there and is the reason for aeroplane blast that kills 140 people. She also comes to know that the terror outfit’s next plane is something as big as 9/11. How she unearths the plot with a journalist Riyaaz ‘s (Vivek) aid and what it all leads forms the rest of the plot.