In a bridge across a sea, saxophone music is heard which is played by Guna (Prabhu). He recollects about the tragedy which happened two years back in his life.
Guna and Siva (Ramesh Aravind) are two brothers who own an orchestra and are very popular with their performances. Both are very affectionate towards each other. Both of them look for their love and eventually find one. The girl whom Siva chose accepted his love, while the girl chose by Guna insults him of his fat size, which hurts him. Siva’s love fails and he is heartbroken. To console him, Guna shifts to city with Siva and his sister. Guna’s father had an illegal affair with a woman named Sitamma during their childhood, and on his deathbed, his father gets a promise from Guna that he should accommodate her with them as she does not have any relation. Guna, who lost his mother invites her to live with them. Sitamma accepts on condition that nobody in the family should know how she is related to them and also she should be introduced as a cook. Unwillingly, Guna accepts that. Guna, being a saxophone player, music director and lyricist, and Siva as a singer flourish in their career. Sitamma finds that Guna is a very affectionate person and Siva is a very sensitive person who cannot bear any downfalls in life even to a little extent.

Ravi, a shopkeeper, falls in love with Uma, a student, who belongs to a rich family. But their relationship is tested when Uma’s brother decides to intervene and break their bond.

Karthikeyan (Arjun) is a photographer-editor working in Indian Express. Chitra (Meena) is a bank employee. Both reside in Navi Mumbai. Karthik meets Chitra while opening a bank account. While returning home, he again meets her in a train. He offers his seat, but she does not want to accept it. During a train strike, he invites her to travel in an auto to reduce expenses, but she declines. When Chitra hesitated to travel in the same train with Karthik, he became angry and explained that he talked to her because both are from the same locality, both are Tamilians, and he promises her that he will never talk to her anymore. After some days Chitra voluntarily talks to him. Karthik, in return, accompanies her to a police station to get back her snatched handbag. Karthik invites Chitra to his home to meet his parents.
Karthik’s parents like Chitra and all become friends. Karthik’s mother requests Chitra to tell Karthik to get married. When she conveys his parent’s wish, Karthik explains about his wife Aruna (Jyothika), who died in a train accident. Karthik learns that Chitra’s husband Srikanth (Ramesh Aravind) died in the same train accident. Chitra adopted a boy, Shiva, as per her husband’s wish. Karthik’s parents want them to get married.
Shiva moves close to Karthik and his family, while Chitra tries to prevent relations with Karthik. Karthik’s father (Nagesh) understands Karthik’s interest towards Chitra. He asks her to marry Karthik. She refuses, and once for all, avoids Karthik. Karthik understood her intention and stayed away from her. Chitra meanwhile gets confused regarding second marriage due to the trouble given by her neighbour’s husband and Shiva’s passion for Karthik. Chitra’s neighbour once attempts to rape her; she manages to escape. Karthik, who heard about it, attacks the man for misbehaving, and makes him vacate Mumbai.
Chitra decides to marry Karthik for herself and her son. She plans to meet him at the station to express her decision. While returning home, she meets her mother-in-law (Lakshmi), who at one time opposed the marriage of her son Srikanth with her. Chitra’s mother-in-law requests her to come and live with her as she is very alone after her husband’s death. Chitra leaves with her mother-in-law. She has not dared to meet Karthik and she leaves without informing him. Karthik and his family are very much disappointed by this.
After some months, Chitra panics on seeing a news about a bomb blast at Mumbai Indian Express and verifies Karthik’s safety. Karthik leaves for Coonoor on an official assignment. There he meets Chitra with her mother-in-law. Chitra introduces him to her and tells about Aruna’s death in the same train accident where Srikanth died. On hearing this, Chitra’s mother-in-law invites Karthik to have lunch with them the next day. This delights Shiva. He eagerly waits for Karthik and leaves school well before, but is stuck in a traffic jam for a long time. Meanwhile, Chitra explains about her decision to marry him, and later changed it as her mother-in-law requested her to live with her. Karthik leaves without meeting Shiva to catch the train. This disappoints Shiva. When Chitra tried to console him, he blames her that she did not keep up the promise that he, Chitra, Karthik, and his parents to live together. Chitra’s mother-in-law hears this, understood the meaning of it and she realised the mistake she made. She catches Karthik at the station and requests him to marry Chitra. Karthik and Chitra leave for Mumbai and get married, which delights Shiva and Karthik’s parents.

Arun (Ramesh Arvind) is married to Leelavathi (Kalpana) in a forced marriage. He is embarrassed by his wife’s plain looks and her weight. When he meets Priya (Heera Rajagopal) – who works in a building construction company, he hides from her the fact that he is married and has an affair with her.
When he takes Priya with him on a vacation to Bangalore, he bumps into his old friend Dr. Sakthivel Gounder (Kamal Haasan) – an orthopedic surgeon from Coimbatore who is also in Bangalore with his wife Palani (Kovai Sarala) and his son Anand – travelling with him in the same flight and even staying in the same hotel. Sakthivel is called to Arun’s room in the night – as Arun has slipped his disc and the hotel doctor is unavailable – and bumps into Priya, thus finding out about the affair.