Ever since his son died in a car accident six years ago, Dr. Ranveer (Amitabh Bachchan) has been very protective of his daughter Ria (Bipasha Basu). While walking home on a rainy night from college, Ria gets frightened as a gang of motorcyclists zoom by her, making her drop her umbrella. She yells at them until they stop feet away and when one of the men (John Abraham) removes his helmet and walks over to Ria, helping her pick up her wet notebooks.
On another day Ria and her friends go to a club and the man who had helped Ria approaches her while at the bar. She is surprised to meet him again and is stunned when he tells her that he has been thinking about her ever since that rainy night. He forces her to dance, and there she feels something for him then but she does not want to admit it. Dr. Ranveer shows up asking for Ria. The man introduces himself as Aryan before she leaves. Dr. Ranveer wants to take Ria home. Aryan goes with his friends to a brothel where a prostitute named Saira teases Aryan and angers him when she asks him to sleep with her to which he refuses. He takes her in a dark room where she thinks they are going to have sex, but Aryan brutally beats her up. Dr. Ranveer is called to the hospital to treat her.
The next morning, Aryan walks into Ria's class and takes her to his place where he shows her a portrait he made of her the first night they met. When she tells him it's beautiful, more beautiful than her, he lights it on fire and tells her that there's nothing in the world that is better than her. She runs out of his apartment terrified, but realizes that she's fallen in love with him. They begin to spend time together and he asks her if they can meet the next day. Ria walks into her house joyous and totally in love where she learns that her parents have planned a surprise vacation to a cabin they rented for four days. Ria tells her parents that she does not want to miss out on any school, but they assure her she will not. They go to the cabin and Ria thinks about Aryan, who is at his house looking gradually at the clock as hours pass by waiting for Ria. He then smashes his clock in rage. Ria cleans around the cabin and looks out the window to see Aryan. She rushes outside to look for him but does not see him, until he strangles her saying that she deceived him and was trying to get away from him. He lets her go and she explains she left for her father's happiness and explains the horrific day of the car accident six years ago that hospitalized Dr. Ranveer for six months but killed her brother. Aryan apologizes and tells her that her father only has a place in her heart and that he has everything else. They spend the next three days together and Dr. Ranveer spots them together at Aryan's place. He takes Ria home and tells her to call him over for tea. She is thrilled and when Aryan comes over, he makes a good impression on her mother (Supriya Pilgaonkar), but not her father and Aryan tells Ria that he sensed that. Dr. Ranveer tells his wife that he's seen Aryan somewhere before and that it is something disturbing.
Aryan tries to steal a car with his friends so that they can sell it for money. But one of his friends gets injured in the process. They take him to the hospital. Dr. Ranveer tells the prostitute Saira that her wounds will heal eventually and then she spots Aryan, who is stunned to see Dr. Ranveer treating Saira, but he does not see Aryan. Saira tries to tell Dr. Ranveer that Aryan beat her, but Dr. Ranveer does not see Aryan's face.
One day while trying to find a colleague's phone number, Dr. Ranveer finds an old article about Aryan saying that he killed his own father and he shows Ria and his wife. Ria confronts Aryan about this, and he tells her that he did kill his father for the sake of his mother because his father was drunk and he would beat his mother everyday and one day from college he finds out that his mother had died. So he burnt his father alive. Ria then apologizes and they make up. She tries to explain to her father, but he refuses to believe Aryan's innocence, pointing that he was still a killer. Ria then yells at her father saying that he's so over-protective just because his son died, and that he's making everyone miserable and Ria's mother slaps her and Ria tells them that she hates them.
Dr. Ranveer decides to dig deeper and finds out that Aryan's mother is alive and the reason Aryan killed his father was because Aryan was in love with his college teacher named Sanjana. She was leaving the city and getting married when Aryan goes to her house and tries to kill. His father intervenes with the police and Aryan is locked up in his room. Sanjana stops by his house to thank his father and she leaves, and Aryan snaps. The parents see a fire starting inside Aryan's room. His father busts through the door where Aryan hurls him into the fire.
Dr. Ranveer devises a plan to lure Aryan into believing that Sanjana is back to warn Ria about Aryan and he finds out that it was just a trick to show Ria his true self. Ria feels horrible that she trusted and loved someone like him and Aryan gets dragged away by the police for attempting to kill "Sanjana", who was really Ria's friend. A while later, Dr. Ranveer gets a call saying that Aryan has escaped from prison. Ria tells her parents that he knows they are at the factory and will come and get her and if she refuses to leave with him, he will kill her.
Aryan arrives with his friends and breaks into the factory. Aryan sends his men to look for the family, kill the parents and bring Ria to him so that he could kill her himself. Dr. Ranveer kills the men one by one and when he confronts Aryan, Dr. Ranveer and Aryan fight until Aryan knocks him unconscious. Aryan goes after Ria & her mother. He is about to hit Ria when Dr. Ranveer comes from behind and attacks Aryan. Aryan breaks off a plank of wood and hits Dr. Ranveer and then goes after Ria and her mother. Dr. Ranveer pulls an anchor attached to a rope which goes through Aryan, killing him.
The next morning Dr. Ranveer drops Ria off at college and tells her that she needs to be strong and not think of this again. She runs into her friends who joke and laugh with her as Dr. Ranveer looks at his daughter smiling and he wipes away a tear from his eye, knowing that everything is back to normal.Amitabh Bachchan as Dr. Ranveer Malhotra ,A doctor from Mumbai who protected his daughter Ria but failed to protect his son Rohit.
John Abraham as Aryan Trivedi, A deadly and obsessed man who is madly in love with Ria.
Bipasha Basu as Ria Malhotra, A young college student who is also Sheetal & Ranveer's daughter.
Supriya Pilgaonkar as Sheetal Malhotra, Ranveer's wife and Ria's mother.
Ali Asgar as Deepak, Ria's friend
Amardeep Jha as Mrs. Trivedi, Aryan's mother.
Tom Alter as Dr. Freddie, Ranveer's friend.
Pramod Moutho as Police Commissioner
Shruti Ulfat as Sanjana, Aryan's college teacher who left for America to get married.
Prithvi Zutshi as Dev Trivedi, Aryan's father who was burnt alive.
Deepak Shirke as Police Inspector