Babu (Dhanush) is a struggling youngster who makes a living out of selling milk tea, carrying the business on his bicycle. He falls in love with a college girl named Uma (Sridevi Vijaykumar). Gradually, Uma also reciprocates Babu's feelings and things go smoothly for a while. Uma's parents find her a wealthy groom who is well educated. Uma is in a dilemma on whom to choose as her life partner. She thinks of her future if she chooses the impoverished Babu where she visualizes herself giving birth to a child in a government hospital, her husband unable to raise required money for her medical expenses and overall a very difficult life; in contrast to a life where she is pampered by everyone, her every need taken care of almost instantly if she chooses to marry the groom selected by her parents. While Babu is on a religious trip to Sabarimala, the girl decides to marry the groom Bala (Kunal) so that she can continue to lead a comfortable life. Babu is devastated when he learns of this and heartbroken when Uma goes to the extent of slapping him when he accuses her parents of changing her mind. In a unique way, Babu files a case against Uma for not holding the promise made to him of sharing a life together for a good 50 years. The case soon gathers momentum and has the public discussing it everywhere. As the case progresses, several sacrifices made by Babu for the sake of Uma come into light through revelations made by people known to him and by his close friends. Uma has a change of heart and on the final day of the hearing, decides to re-unite with Babu. In a final twist, when Uma offers a rose to Babu, he refuses to accept her, saying that the case was filed not to win her back, but to teach a lesson to her and every girl with an attitude identical. He justifies further by saying that yesterday she hated him because of his status but today she loves him and tomorrow she may again find him unattractive. Feeling light at heart, he leaves the court complex much to the surprise of the visibly embarrassed Uma.