Dinakaran Dinakaran, whom his friends nicknamed Atta, grows up as a regular semi-urban teenager in a small village on the outskirts of Chennai. He breezes through school with decent marks, yet he fails his English paper, and instead of hitting the books for a retake, he leans into a lighthearted quest for romance, part of a pact with his closest friends to fall in love and get married.
His first crush lands at the bus stop, where Poornima smiles at him and accepts his gifts. But when he starts pursuing her, she refers to him as an elder brother and asks him to stop following her around, signaling that the spark may have been more fantasy than real feeling. Dinakaran tries to feel sad, but the sting doesn’t linger—he realizes it was never true love, just a phase.
Next comes an attempt to woo a distant relative who visits his home; she, however, falls for his elder brother. He then finds himself on the receiving end of rough treatment from boys in a neighboring village for chasing two of their girls. To shield himself and impress the girls, he turns to martial arts, but nothing in that path changes the outcome.
Eventually, Dinakaran decides to focus on his studies. He passes the English exam and enrolls in the local college. There, a new world opens up under the wing of an overprotective senior, a self-proclaimed underground student leader whom everyone calls the route thala or the designated don of the route. Dinakaran’s life pivots as he drifts into the wrong crowd—becoming less sociable and more prone to fights. When his senior graduates, Dinakaran is chosen as the next route thala, a role he takes seriously and gradually earns both respect and fear from the student body.
A new junior arrives—his childhood friend and one of the girls he once chased, Poornima—and Dinakaran tries to keep his distance. Yet the old spark flickers back, and he finds himself drawn to her again, especially when she shows him an old bus ticket he had bought for her. He becomes convinced that she loves him too, and he even reverts to his old haircut and style because Poornima prefers it; his family and friends tease him, but her compliment on the new look becomes enough to quiet the mockery.
Trouble soon follows when Poornima’s family learns of her love for someone they disapprove of and schemes an arranged marriage for her. Dinakaran gathers his old friends to help, and their plan suggests eloping with Poornima with the help of their kin, though one friend questions whether Poornima has a say in the decision. Impatient, Dinakaran pursues Poornima and ends up in a confrontation with her elder brother, eventually escaping and waiting at the meeting place, only for Poornima to fail to show.
Dinakaran boards the public bus home and unexpectedly runs into Poornima, where the truth emerges: she was never in love with him; her real beloved is another boy named Dinakaran, which leads her family to believe he is the target. While they chase the mistaken fiancé, Poornima has already married the other Dinakaran and is on her way to a movie with her new husband. The heartbreak hits hard, but Dinakaran regroups quickly, recognizing that this phase was just infatuation and not genuine love.
The story closes with a retrospective glimpse: Dinakaran studies hard, becomes a teacher, and continues to care for his mother, eventually finding his own path to happiness and an eventual marriage. Post-credits scenes reinforce the message of growth, resilience, and moving forward after the storm.
