Billu is the son of Mudaliar. Mudaliar is much loved and respected by the people of his locality, and Billu is almost like a foster son to everyone there. Billu takes an instant liking for Susi the moment he sets his eyes on her at the railway station. Susi, who has arrived from Bangalore to Chennai, is all set to stay at Settu's place. Settu, who has worked for Susi's father Chidambaram, a dreaded criminal, has earlier changed ways but still respects him. Susi, who has wanted love and concern since she was young, is impressed by the bonding that the Royapuram residents share. When a godman predicts that Susi is the one for Billu, she is taken aback. She dreads her father and fears that things will go topsy-turvy if their relationship blossoms into love. Soon, she realizes she cannot hide her feelings towards Billu and enjoys being in the company of Billu and his friends, but the unexpected occurs. Susi acts peculiar when a long-lost friend meets her at a restaurant. She denies knowing her, despite her friend Revathi's attempts to talk to her. Feeling insulted, Revathi walks away, much to the dismay and confusion of Billu and his friends. Susi, who gets emotionally high-strung, leaves the restaurant in a jiffy, too. Susi, at this juncture, reveals the truth to Billu. Affected with
PTSD after an accident, Susi has forgotten events that happened in a span of three years. Billu, who takes her to Dr. Devasaghayam, learns that this condition can be cured, but when Susi gets cured, she will not be in a position to remember what happened and who she met at Chennai, including Billu. This greatly disheartens Susi, and she persuades Billu to promise never to leave her, even if she were to forget him due to her condition. Billu promises her that he will never leave her, come what may. Billu's conversation with Chidambaram infuriates the latter, and he immediately arrives in Chennai with his goons. When he is all set to leave for Bangalore with his daughter, the residents rise to the occasion and flock against Chidambaram. Deciding to play it safe, Chidambaram agrees to the engagement between Billu and Susi and cunningly thrashes Billu after making him arrive at a place far from his locality, at the outskirts. The helpless Susi travels along with her father, escorted by his men, to Bangalore. When Billu meets Susi at her residence, he gets nothing less than shocked as she has been cured, and she fails to recognize him, but Billu, who had given the word to his beloved that he would never leave her, is not the one to relent. In the end, he tries relentlessly to convince her, going to the extent of bringing her to Royapuram despite her resistance. Chidambaram comes there with his men, and a fight ensues. Billu is disheartened as Chidambaram drags Susi away, as Susi gets surprised by Billu and the Royapuram residents' behavior towards her earlier. She leaves her father's hands and suddenly runs to Billu. Billu becomes elated that Susi has regained her memories, but Susi reveals that she does not remember anything but believes whatever he says about her life in Chennai. They finally reunite. ==Cast==