Prasanna is a young man who indulges in several revolutionary activities against the wishes of his father Mahendran, a widower. After Prasanna tells him that, due to the price of rice increasing, he stole rice from a lorry, distributed it to the poor and set fire to the lorry before the police arrived, a disgusted Mahendran helps the police arrest him, widening the already existing rift between them. After his release, Prasanna opts to stay away from his hometown, Bangalore, and reaches Madras.

One day, Prasanna is beaten up for abusing the passengers of a car that splashed water on him. Carnatic singer Bhairavi, returning home after a katcheri, notices him lying unconscious on the roadside, takes him home and her doctor friend Suri treats him. At Bhairavi's request, Prasanna continues to live in her house even after he recovers. He slowly develops passionate feelings for her even though she is much older.

Before Prasanna's arrival, Bhairavi's daughter Ranjani, who believes she was adopted, learns that she is actually Bhairavi's biological daughter born out of wedlock. Unable to digest her mother's hypocrisy, she runs away from home and meets Mahendran in Bangalore while trying to sell some items. She ends up staying at his house for a few days at his request. Impressed by his love for his deceased wife, his longing for his son Prasanna who left him, and his commitment to help her, she expresses a desire to marry him, despite the fact that he is old enough to be her father.

Both Bhairavi and Mahendran reject Prasanna and Ranjani's proposals, citing their age difference and other situations, but with perseverance, Prasanna and Ranjani are able to convince them that their respective marriages could work. Bhairavi is forced to accept Prasanna's proposal when he ends his revolutionary activities and takes up music for her sake, becoming a mridangam player. Prasanna is happy that Bhairavi has accepted his proposal, but Pandiyan, her ex-lover and Ranjani's father, turns up to meet her and to apologise. Prasanna does not allow this and, as Pandiyan is dying from blood cancer, takes him away for treatment at his place. He tells Pandiyan of his plan to marry Bhairavi and seeks his co-operation. Pandiyan agrees not to meet her.

Mahendran, seeing an advertisement placed by Bhairavi about her missing daughter, comes to meet Bhairavi at her house and sees Prasanna's photograph there. He realises they are in love. Mahendran advertises for his missing son. Bhairavi sees the advertisement so she tells Prasanna to get his father's consent before marrying her. They both meet Mahendran, who introduces Ranjani as Prasanna's future mother since she is his future wife. A riddle is explained: Prasanna's wife will be the mother of his father's wife, meaning Ranjani will be the mother-in-law of her own mother and Mahendran will be the son-in-law of his own son. Mahendran asks Prasanna how this riddle is going to be cleared in their case.

During Bhairavi's next katcheri, where Prasanna is a mridangam player, she sings "Kelviyin Nayagane, Indha Kelvikku Badhil Edhayya?" (Oh hero of the question, what is the answer to this question?). Ranjani changes her mind and joins her mother by singing at the concert. Observing this, Prasanna also changes his mind and joins his father. When all these issues are cleared, Pandiyan sends a note to Bhairavi in the middle of the katcheri. Bhairavi searches for him after it ends and finds him dead with a note in his hand, wishing her well with Prasanna. She erases the kumkuma from her forehead to declare herself a widow and leaves with Ranjani, while Prasanna joins Mahendran.