Palakkad Madhavan is a naïve and aspiring music director. His assistant Gopi is a dholak player. Arriving in Madras, looking for a chance in music direction, they rent a thatched room on the terrace of the house of Vasanthi, a young woman. Madhavan commences his hunt for a chance in films, but does not succeed and struggles in penury. Madhavan's talents impress Vasanthi and soon she falls in love with him. However, Madhavan is reluctant and avoids her as he is still not settled in life. When he realises that she loves him despite his situation, he reciprocates.

Vasanthi's family is in deep financial trouble; to clear their debts, they arrange her marriage with Anand, a wealthy widower with a daughter. Seeing the plight of Vasanthi, Madhavan agrees to marry her secretly in a temple. However, just before the wedding, Vasanthi's family members and relatives arrive at the venue, attack Madhavan and take Vasanthi away. Vasanthi is forcibly married to Anand. On their wedding night, Vasanthi consumes poison but is saved in time by Anand, a doctor by profession.

Vasanthi tells Anand about her past, and he promises to send her back to Madhavan with just one request. He had agreed to remarriage due to pressure from his mother who is terminally ill and unlikely to survive for more than seven days. He requests Vasanthi to pretend to be his wife for these seven days so that his mother can die peacefully, after which Vasanthi can go back to Madhavan. She agrees, but at the same time slowly starts accepting his family and becomes close to Anand's daughter.

Anand locates Madhavan, poses as a film producer and offers Madhavan a chance to compose music for his next film. Madhavan agrees and starts composing music. Anand narrates the love story of Madhavan and Vasanthi and Vasanthi's wedding to Madhavan as the film's plot step by step, but with a different backdrop. Madhavan does not realise that the story being narrated is his real story and fervently focuses on song composition.

After Anand's mother dies on the seventh day, Anand invites Madhavan to come to his home for a discussion. He continues the story to the stage when the sick mother-in-law dies, and the heroine leaves her husband's home to live with her lover. He then asks Madhavan's opinion about the unusual climax. Though Madhavan does not like it, he appreciates it to please the "producer".

Anand takes Madhavan to his room, ostensibly to give him an advance, but instead offers Vasanthi to him. Madhavan initially hesitates, but soon agrees on the condition that Vasanthi only come in the same way when she was his love, without the thaali. Vasanthi, however, cannot bring herself to remove it. When Anand tries to, she resists. Madhavan then tells Anand that Madhavan's lover can be Anand's wife, but Anand's wife can never be Madhavan's lover again. He concludes that adhering to traditional values is the right ending, wishes the couple well and leaves.