Raj Malhotra (Akshay Kumar) is employed by a telecommunications company, Air Voice. Priya Saxena (Kareena Kapoor)—who is looking for a full-time job—goes to Raj's house for an interview, mistaking him for barrister Ram Chautrani (Annu Kapoor), a neighbour and Raj's friend. Raj and Priya fall in love, marry and are expecting their first child. Raj expects to be promoted to CEO when the company's chairman (Amrish Puri) arrives with his new wife, Sonia Roy (Priyanka Chopra) to announce the promotions. Sonia Roy is named the company's new chairman; after a discussion with her husband, she announces the promotions. The CEO position goes to Raj's friend Rakesh (Vivek Shauq), and Raj is named to the board of directors. At a party, Raj brings Priya and learns about his new boss, Sonia Roy. Priya is surprised that Sonia is the wife of the former chairman (and half his age). Raj and his colleagues talk about Sonia Roy and the age difference between her and her husband, and Raj jokes that his magnetic personality was responsible for his promotion.
A flashback explores Raj's previous relationship with Sonia. Five years earlier, Raj and Sonia (then a model) meet at a beach in Cape Town. They fall in love and move in together; Sonia becomes pregnant with Raj's child,which makes him happy. But Sonia refuses Raj's marriage proposal and says she is going to terminate the pregnancy. She wants wealth, fame, power and status, and a child would be in the way; their relationship ends. As that was a past between Raj and Sonia,at the party,Sonia was flirting with Raj,even in front of his wife Priya. So,after the party,Priya requests Raj to stay away from Sonia. After Raj and Sonia flashback ends,Priya gets pregnant.
On the next day, Rakesh tells Raj about a defect in the company's new mobile handset: a call goes to two people simultaneously—the intended recipient and another person on the phone's contact list. Raj needs Sonia's permission to halt production, and she invites him to her house to discuss the matter.
Sonia aggressively tries to pursue Raj, who resists. Although he repeatedly rejects her advances, Sonia continues trying to seduce him. For a moment it seems that Raj has given in to Sonia's advances but after looking at his locket which has Priya's portrait in it, Raj realizes what he is doing and tries to leave. As Raj leaves, she threatens to punish him for spurning her. The next day, he learns that Sonia has told her husband that Raj harassed her sexually. Since he has admitted finding Sonia attractive his claim of innocence is not believed, and the company pressures him into a resignation.
Raj asks Ram Chauthrani to take his case; Chauthrani tells him not to resign, and to keep going to work. The case goes to court; Sonia and Roy engage a lawyer, Patel (Paresh Rawal). Although the bulk of the evidence is at first against Raj, his friend returns from Bangkok and gives him a tape which recorded Raj's encounter at Sonia's house. After the tape is proven genuine, Chauthrani is struck by a car driven by someone hired by Sonia and the tape is substituted.
When Priya asks Raj why he called their bank manager from Sonia's house, he replies that he had called Rakesh; the call went through to the bank manager as well. Priya (also a lawyer) continues the case after Chauthrani's injury. She uses Rakesh's phone in evidence against Sonia, exposing her earlier relationship with Raj. It is revealed that Sonia married Roy for money, power and status; when he could not satisfy her sexually, she tried to resume her relationship with Raj. Priya wins the case, and Roy leaves Sonia. Guilt-stricken and humiliated, Sonia commits suicide by jumping from a building.