Kundavi, Jyothika grows up in a small town called Ambasamudram in the Tirunelveli district, and dreams of a love marriage with two close friends, a dream that faces stubborn obstacles. Her father arranges her marriage to Gowtham, Suriya, against her wishes, casting a somber mood over the wedding and leaving both of them looking uneasy.
Six years later in Mumbai, Kundavi and Gowtham share a life of quiet affection with a five-year-old daughter Ishwarya, Bhumika Chawla. Gowtham works as the chief mechanical engineer at Maruti Suzuki, while Kundavi holds a job at a local call centre, and their home feels like a small haven of happiness despite the early tensions of their arranged past.
Gowtham travels to New York City for a short period, and during this time Kundavi stumbles upon Gowtham’s old college diary. The diary reveals Gowtham’s long-held dream to become an engineer, and how he pulled strings to secure a seat in Coimbatore. From the second year of college he is known as a dominant figure, a “don” in the campus lore. In college, he is drawn to Ishwarya, the daughter of a Member of Parliament from Coimbatore, and the two fall deeply in love with plans to marry. At the registrar’s office, after Gowtham ties the knot, Ishwarya’s father and his men beat him up, ripping apart the lovers and sending Ishwarya off to Sydney, Australia. At the end of the diary, Gowtham writes a note: > If I have one wish, it would be to live with Ishwarya happily at least for one day. Then, by his uncle’s last wish on his deathbed, Gowtham agrees to marry Kundavi.
Gowtham returns from New York and finds his wife changed. She works late and avoids him, and Kundavi realizes he still loves her deeply and that his lost love has returned from Australia. Ishwarya has grown into a modern girl, a stark contrast to the demure salwar kameez girl she once was in college, and she even completely ignores her father at the airport because of past behavior toward him. Kundavi asks Ishwarya to visit them and tells Gowtham that he should live happily with Ishwarya for a day, and that for that day, she and their daughter do not exist for him, before leaving Gowtham in Ishwarya’s care.
Gowtham spends the day with Ishwarya, traveling to many places, revisiting memories, and rekindling their shared affection. They rediscover the depth of their love, reminisce about what they missed during the six years apart, and grow close once more, even sharing a moment of intimacy. It is then revealed that all of this was merely Kundavi’s dream. Panicked by the dream, Kundavi returns home to find her husband alone and asks where Ishwarya is, discovering Ishwarya’s letter. In it, Ishwarya explains that Kundavi gave them a day, but a full hour was enough for them: 40 minutes of silence, 10 minutes of formal inquiries, and 10 minutes of talking. Even in that brief 10-minute exchange, the only word Gowtham uttered was “Kundavi.” Ishwarya realizes that Gowtham and Kundavi are deeply in love and deserve a happy life together, and she wishes the couple well, choosing to leave and never return.
In the end, Gowtham confesses that he kept his inner truth hidden to protect Kundavi’s feelings, aware that no other girl would accept sharing her husband. Yet Kundavi has brought the woman Gowtham loved into their life to make him happy, and the two cry in happiness and hug as Diwali fireworks bloom in the sky. Their daughter Ishu joins them, and the movie closes on a hopeful, joyous note.
