Silambarasan Rajendar, Trisha Krishnan
A. R. Rahman
Karthik (Silambarasan) is a student of mechanical engineering in Chennai who aspires to become a filmmaker. His friend introduces him to cinematographer Ganesh (Ganesh Janardhanan). With Ganesh's help Karthik becomes an assistant to director K. S. Ravikumar. Karthik's family, who are Hindu Vellalars, rent Jessie's (Trisha Krishnan) house. Jessie is from a conservative Nasrani Christian family from Alappuzha, Kerala, that lives upstairs. Karthik falls in love with Jessie the moment he meets her.
Karthik tries to interact with Jessie, who is afraid of speaking to men around her strict father, and ends up angering her. Unable to hide his feelings any longer, Karthik confesses his love for her; she does not respond. A few days later, Karthik learns from his sister that Jessie has gone to Kerala to visit her grandmother. He and Ganesh end up in Kerala to look for her. After several days, he finds her and apologises. She introduces him to her family in Kerala as her "classmate". Jessie denies she has any feelings for him but agrees to be his friend. On the train journey back home, however, the two get close and share a kiss. Karthik is convinced Jessie loves him; the two meet several times and Jessie begins to admit that she also likes Karthik, but wants to refrain from any problems because she knows her father wouldn't give her hand in marriage to a Hindu.
Consequently, due to various misunderstandings between Jessie's brother and Karthik, her parents learn of their supposed affair. They fix a match and schedule her wedding. The day arrives and midway through the ceremony, Jessie refuses to marry the groom, displeasing everyone in her family. Karthik, who had, without anyone's knowledge, come to Kerala to witness the wedding is ecstatic and secretly visits Jessie at her home. It is then that Jessie admits she has indeed fallen in love with him. Karthik and Jessie continue to love each other without the knowledge of their parents.
At this point of time, Karthik goes to Goa on a 45-day shoot, where he gets rather busy. Meanwhile, the topic of Jessie's marriage comes up again at her home when the guy whom she refused to marry earlier pays them a visit. Panicking, Jessie calls Karthik and tells him that she wants to elope with him. Karthik, since he is travelling through less than ideal places, tells Jessie to stay in Chennai for now, and that soon he would be back and they can discuss. Jessie stops taking Karthik's calls and so he goes back one night to check on Jessie. He comes to know that Jessie has decided to break up, as the relationship is not peaceful due to her parents' disapproval. She says she has agreed to get married to a boy of their choice. When Karthik pleads her not to do it, she tells him that a time had come when she was willing to elope, but the moment was gone. She doesn't want Karthik to wait for her too long, as he has his dreams to fulfill. Karthik later comes to know that she is married and settled abroad.
Two years later, Karthik meets Nandhini (Samantha Ruth Prabhu). She falls in love with him, but is rejected by Karthik by saying that he hasn't yet gotten over Jessie. He then comes up with a script for his first film, which happens to be his very own love story. He calls upon Naga Chaitanya Akkineni as the film's protagonist, Nandhini as the female lead and Ganesh as the film's cinematographer, and the film is eventually titled Jessie. While shooting for the film in New York, he sees Jessie and she comes to speak with him. She admits that she is not married and is still in love with him, and he too says she is still in his heart.
Karthik proposes yet again and they get married the same day. This is actually revealed to be the end scene in Karthik's movie – which Karthik and Jessie in real life are watching together in the theatre. After it gets over, it is revealed to the audience that Jessie had in fact seen Karthik in New York but had not come forward to meet him. She is married now and hence asks Karthik to fall in love again and move on. She tells Karthik that they cannot lead a life which is full of obstacles and they part, once and for all to lead different lives and different destinies.