Ashok (Karthik Muthuraman) attends a job interview in which the interviewer turns out to be his father, Vishwanath's (Vijayakumar), high school friend. The interviewer asks personal questions and it is revealed that Ashok is Vishwanath’s second wife Kamala's (Jayachitra), son. More personal questions anger Ashok and he beats the interviewer and storms out.
Gautham (Prabhu Ganesan) is a police academy trainee and during a routine boxing match, he goes overboard and beats up his opponent even after the referee has stopped the fight. The police commissioner reprimands Gautham and asks him not to take out his anger towards his father, Vishwanath, on someone else.
Ashok returns home to his mother, sister Mallika (Tara) and his inebriated father. His mother asks him to take his father to his first wife Susheela (Sumitra) home. Ashok initially protests but relents to take him home. After the ride, Gautham comes to the door and helps his father into home. There is a brief moment of animosity between Gautham and Ashok and it is clear that both the half-brothers hate each other.
During a party at the Police Commissioner’s house, Gautham meets the Commissioner’s daughter, Anjali (Amala) when he covers for her smoking. One day, when Ashok is just hanging out with his friends, a girl Anitha (Nirosha), looks at him, shouts "I love you" and drives away. A stunned Ashok tries to follow her but loses her in the traffic. Vishwanath is appointed the head of an inquiry commission to probe a chemical factory, owned by Chidambaram (G. Umapathy), believed to sell chemicals to terrorists.
Gautham graduates from the academy & is appointed as an Assistant Commissioner and Anjali and him fall in love with each other. Ashok runs into Anitha again but this time he memorizes her car number. He traces her address by bribing a transport officer, goes to her home and says "I love you" to a surprised Anitha.
Ashok and his friends run into Gautham and Anjali which prompts one of Ashok's friends to tease Gautham. Gautham soon stops Ashok's friend while he is riding his motorbike and asks for his license. When he shows it, Gautham throws it away and arrests him for driving without a license but instructs his constables to release him after a couple of hours. A peeved Ashok goes to Gautham's place and stones it causing an accidental injury to Gautham's mother Susheela.
The next day, Gautham tries to arrest Ashok but Ashok teases him that he doesn't have a warrant and cannot be arrested. Gautham accuses Ashok's parentage which causes Ashok to lose his cool and tries to assault Gautham. Gautham then arrests Ashok on charges of assaulting an officer of the law. Since Vishwanath is out of town, Susheela helps Kamala bailout Ashok.
Chidambaram visits Vishwanath at his office and later at both his homes and tries to bribe him but each time Vishwanath rebuffs him. An irked Chidambaram warns to put a hit on Vishwanath if he still continues with his investigation.
On the day when Ashok's sister is to be asked for her hand in marriage, Vishwanath fails to turn up which causes the groom's family to question the marriage between Kamala and Vishwanath. An angry Ashok goes to Vishwanath's home and creates a ruckus only to realize that his grandmother, Vishwanath's mother Rajamma (S. N. Lakshmi) has died. Gautham, angered by the scene caused by Ashok, throws him out.
Anitha visits Ashok at his home uninvited and falsely tells him that she is pregnant with his child in front of his mother to get him in trouble. Ashok finds her having lunch with her father and enquires about her pregnancy to scare her. But he stops once he learns that Anitha too comes from a broken home.
One day, when Ashok's sister is travelling by train she runs into Gautham and Anjali, so Gautham gets into the next train car. After he leaves, Chidambaram's men harass and threaten the sister. She runs away and tells Gautham and Gautham saves her. While dropping her off at her home, Ashok throws Gautham out of his house.
Another altercation occurs at a wedding in which both exchange words. The next day, Ashok finds Gautham and both get into a huge brawl, which Vishwanath witnesses. Vishwanath berates both of them and gives up hope on both of them ever getting along with each other. While Vishwanath is leaving his office, he gets run over by a truck driven by one of Chidambaram's thugs.
Vishwanath survives with severe injuries and goes into a coma. Mutual fear between the families brings them closer as both Susheela and Kamala wait by his bedside. Ashok threatens Chidambaram with dire consequences if his father dies. Gautham tracks down the truck driver and arrests him. Unhappy that Vishwanath survived, Chidambaram arranges for his murder in the hospital. He uses his connections to remove the police security from the hospital and gets the truck driver out on bail. Vishwanath comes out of the coma and asks both his sons to help keep him alive till he presents his evidence against Chidambaram to the commission the next day. When Chidambaram's thugs attack the hospital, the brothers work together to stop the assassination attempt by switching the ambulance in which Vishwanath was in.
The next day, a bandaged Vishwanath is brought into the commission's office by the brothers and Vishwanath submits evidence proving Chidambaram's illegal activities. The movie ends with Gautham arresting Chidambaram and both the brothers embracing each other.
The film has a parallel comedy track which focuses on a rich man (V. K. Ramaswamy) and his chauffeur’s (Janakaraj) quest to ditch their wives and to sleep with a pretty call girl.Prabhu as Gautham
Karthik as Ashok
Amala as Anjali
Vijayakumar as Vishwanath
Nirosha as Anitha
Tara as Mallika
Jayachitra as Kamala, Ashok's mother
Sumithra as Susheela, Gautham's mother
V. K. Ramaswamy
Janagaraj as Lakshmipathi
S. N. Lakshmi as Rajamma, Vishwanath's mother
G.Umapathy (Anand theatre owner) as Chidambaram
The music composed by Ilaiyaraaja. The song "Va Va Anbe Anbe" is set in the raga Shivaranjani.
The film was a commercial success and completed a 200-days run in few theatres. Over the days, it grew popular due to its songs. The film topped the Chennai box office on its opening weekend with ₹10 lakh distributor share.
The film won 2 Filmfare awards, 3 State awards and 5 Cinema Express awards.Filmfare Award for Best Tamil Film
Filmfare Award for Best Actor - Tamil - Karthik
Tamil Nadu State Film Award for Best Film - Mani Ratnam
Tamil Nadu State Film Award Special Prize for Best Actor - Karthik
Tamil Nadu State Film Award for Best Female Playback - K. S. Chitra
Cinema Express Best Tamil Film Award
Cinema Express Best Director Special Award - Mani Ratnam
Cinema Express Best Actress Special Award - Amala ( for Illam as well )
Cinema Express Best New Face - Nirosha ( for Senthoora Poove as well )
Cinema Express Best Music Director - Ilaiyaraaja ( for Soora Samhaaram & Dharmathin Thalaivan as well )