Anu, a talented dancer, finds herself caught in a complex web of love, betrayal, and societal expectations. She initially falls in love with Bharani, a skilled flautist, and their romantic connection blossoms as they dream of a future together. However, her life takes a turn when her father is transferred to Bombay, and she is forced to move there. During this period of separation, Anu’s communication with Bharani becomes increasingly strained; her heartfelt letters go unanswered and she slowly starts to lose hope. When her father falls seriously ill, a colleague named Ramanathan steps in to support their family, offering solace and help.
As her father's condition worsens, Ramanathan proposes marriage to Anu, adding to her emotional turmoil. She is faced with a difficult decision and asks for time to think. Unable to bear the uncertainty, she writes one last letter to Bharani, hoping for a response. But when no reply arrives, Anu chooses to marry Ramanathan, seeking stability amid chaos. Tragically, her father passes away shortly after her wedding, leaving her burdened with grief.
Following her marriage, Anu begins to realize that Ramanathan is not the man she thought he was. His true personality emerges: he is chauvinistic, sadistic, and possessive, which leads him to control and mistreat her. Ramanathan disapproves of her dancing career and forces her to give up her passion. He also becomes suspicious of her fidelity, doubting her character and even questioning the paternity of their newborn son. Unable to endure her husband's abuse and feeling suffocated, Anu decides to divorce Ramanathan. She refuses alimony and returns to Madras to rebuild her life independently.
In Madras, she finds the support of attentive colleagues at her workplace, especially a widower named Janardhan "Johnny", played by Kamal Haasan, who is always ready to listen and help. Johnny, who often communicates through his puppet Junior, offers Anu a place to stay when she has difficulty finding a home. Despite his love and affection for her, Johnny lacks the courage to confess his feelings. When Bharani, her former love and now her neighbor, learns of her situation, he visits her and is devastated to discover that his letters never reached her—an unfortunate coincidence, as they were intercepted by his mentally ill sister. He finally sees Anu again only after her marriage to Ramanathan, by which time she had already moved on. Bharani, heartbroken, chooses to remain single, unable to forget his love for Anu.
Meanwhile, Ramanathan's estranged mother, Leelavathi (played by Leelavathi), recognizes Anu as her daughter-in-law. She feels remorseful for her son's destructive behavior and, in her shame, takes on a disguise to work as Anu’s maid, secretly supporting her. This act of sacrifice leads to a renewed relationship between Anu and Bharani. Leelavathi encourages Anu to pursue happiness and move forward with her life; the two women form a bond of friendship and mutual understanding. They plan to marry, with a civil wedding scheduled.
Unexpectedly, Ramanathan reappears in Madras, claiming to be remorseful and eager to make amends. He does not reveal to Bharani that he is Anu’s former husband. Instead, he subtly tries to rekindle their relationship. Meanwhile, Bharani, aware of Anu's feelings, shares his intentions to marry her. Johnny, observing everything, struggles with his own unspoken love for Anu but continues to support her decision. Leelavathi advises Anu to sever her ties with her past by discarding her mangala sutra and marry Bharani. However, on the day of the wedding, Anu falls ill unexpectedly and cannot meet at the registrar’s office. When Bharani visits her house, he is disappointed to find Ramanathan caring for Anu, which complicates her choosing between her past and present love.
Amidst the emotional chaos, Ramanathan pleads for forgiveness and attempts to convince her to remarry him. At the same time, Anu’s colleague Rajathi, who is familiar with Leelavathi, inadvertently reveals her identity as Anu’s mother-in-law, shocking Anu. Recognizing the pain and betrayal, Anu seeks Leelavathi’s forgiveness. She confides in Johnny, who finally musters the courage to declare his love for her through his puppet Junior. Though touched, Anu understands her own feelings and respectfully asks Johnny to stay her friend rather than pursue a romantic relationship.
As Bharani witnesses the ongoing turmoil and Ramanathan’s manipulations, he decides to leave for abroad to focus on his musical career, stepping back from his love for Anu. Meanwhile, Ramanathan’s true nature is exposed when he reveals that his reformed behavior was merely a ruse to deceive her. Furthermore, another woman appears claiming to be his wife and raising a child, which clearly reveals Ramanathan’s deceit. Realizing she has been manipulated and her dreams shattered, Anu confronts Ramanathan, who openly admits he couldn’t tolerate her happiness. Enraged and hurt, she stops her pursuit of reconciliation, quits her job, and prepares to leave Madras.
Johnny, ever supportive, arranges her travel to Trivandrum. As the train departs, Anu is stunned to see Leelavathi on board. The older woman explains her presence by saying it is her way of seeking forgiveness and peace for her son’s wrongdoings. With tears in her eyes, Anu and Leelavathi embrace, knowing that despite their pain and sacrifices, they are now free from the past’s shadows and can look forward to a future filled with hope and healing.
