Chandrasekhar, Sarath Babu, and Mala, Shanthi Williams, are a married couple whose life together is strained by Mala’s irrational behavior. Mala suspects that Chandrasekhar’s classmate Ramya, Vanitha Krishnachandran, and her husband are having an affair since he visits her often, a doubt that casts a dark shadow over their home. Chandrasekhar learns of Ramya’s love for him only after his marriage to Mala. Ramya remains single and they share a platonic relationship, which antagonises Mala and fuels unfounded jealousy.
Chandrasekhar’s sister Viji, Suhasini Maniratnam, who lives with them, is enthusiastic, fun-loving, and lives on her own terms. One day she bumps into Ram, Mohan, a mechanic with an inferiority complex. Despite initial conflicts, they slowly become friends, their unlikely bond gradually softening the sharp edges of their worlds.
Pratap, Prathap Pothan, a photographer and distant relative of Chandrasekhar, comes to Chennai from Calcutta and meets Viji. Though Pratap likes Viji, he does not propose to her. Ram proposes to Viji, who is unsure whether to accept his suit. However, they become closer, drawn together by shared hopes and the sting of past disappointments.
Viji’s harmless mischief at home with Mala intensifies when Viji mixes chilli powder in Mala’s bath water as punishment for the nuisance Mala creates at home; Mala swears revenge, her pride bruised by the younger sister’s fearless mischief.
Viji accepts Ram’s proposal and informs Chandrasekhar, who advises her to reconsider his decision as he feels they are incompatible. However, seeing her persistence, he approves. Ram’s parents visit Viji’s house to meet Chandrasekhar and take the proposal forward; as he is absent, they meet Mala, who lies to them about an abortion Viji had, as a result of a stray relationship. Shocked, they inform Ram that they have heard this from a doctor, to keep the informer’s identity a secret.
Ram confronts Viji and asks her to clarify, saying he would decide the future course of action based on her reply. Angered with Ram’s lack of trust in her, she ends her relationship with him. Seeing a depressed Viji, Chandrasekhar advises her to marry Pratap, as he is mature enough for her. Initially reluctant, she eventually agrees and marries Pratap. When Viji is leaving for her new life with Pratap, she is further upset when Mala proudly declares that it was she who derailed her wedding with Ram by misleading his parents.
Post marriage, Viji is unable to accept Pratap as her husband and stays aloof. Pratap too is not demanding and patiently waits for her to become normal. Viji is unable to forget her past, and her indifference affects Pratap’s creativity and work.
Ram, in the meantime, has gotten married, and soon moves in with his wife to the same apartment complex as Viji and becomes her neighbour; Viji gets all the more disturbed. Pratap loses his job and plans to relocate to Calcutta. He reserves tickets for Viji as well, but lets her decide if she wants to accompany him.
When Viji is undecided, Ram invites her to his home. He shows her his physically disabled wife, whom he had married to atone for doubting Viji’s character. Ram says that despite his wife’s disability, he tries to live happily with her and asks Viji why she cannot do so with Pratap, who is more qualified than him, instead of thinking about their past and the grouse of losing the life she dreamt of. Realising her mistake of spoiling her present by living in the past, Viji rushes to meet Pratap at the airport and joins him.
