Sub-Inspector Duraisingam "Singam", an honest police officer, lives in Nallur, a small village in
Thoothukudi district in
southern Tamil Nadu, and is assisted by his bumbling colleague Erimalai. Singam belongs to Nallur with his father, Soundarapandi, having a respectable status in the village. His family business is
provision stores, and Singam wants to join it, but he joined the police force due to Soundarapandi's wishes. Singam resolves most of the problems in his village with
non-violence and mutual counselling. He uses force only when the situation demands it, thereby earning great respect and affection from the villagers. Mahalingam, an industrialist in
Chennai and a friend of Soundarapandi, arrives at the village with his daughters Kavya and Divya. Singam initially assumes Kavya is a prankster when she is about to prank her cousin by wearing a tiger costume. While roaming around the village, Singam accidentally slaps Kavya, but later apologizes to her. Kavya gets moved by this and slowly falls in love with him. After some hilarious incidents, Kavya professes her love to Singam. Initially taken aback, Singam reciprocates Kavya's love. Mayil Vaaganam, a
Chennai-based thug infamous for extortion and kidnapping, who often earns money by blackmailing industrialists about their black money to the income tax. One day, Mayil threatens an old industrialist with payment of extortion money, otherwise trapping him in a fake rape case. The old man commits sucide and for that, Mayil is required to travel to Nallur to sign a conditional bail. Mayil instead sends one of his allies to do the formalities, enraging Singam. Singam demands that Mayil sign the bail in person. A humiliated Mayil reaches Nallur, but is unable to take any revenge on Singam, fearing the immense love and devotion of the entire village towards Singam. Using his political contacts, Mayil gets Singam transferred to Chennai to teach him a lesson. Unaware of Mayil's hand behind his transfer, Singam joins
the Thiruvanmiyur police station. His co-worker, SI Ravi, hates Mayil for his crimes, but is unable to take any action because of Mayil's political powers. Singam's senior Rajendran is on Mayil's payroll and takes care in concealing and eliminating evidence of Mayil's crimes. The police commissioner does not help Singam because there is a lack of evidence against Mayil. Rajendran warns Singam to stay away from Mayil's case. Unable to take on Mayil in his stronghold, Singam wants to return to his village, but is stopped by Kavya, who encourages him to fight against Mayil and end his crime network. Being mentally tortured by Mayil, Singam decides to quit the job but is motivated by Kavya and as a result, Singam arrests Mayil's brother, Vaikuntam, in a fake case of illegally smuggling
alcohol. He thwarts Rajendran in full view of the public when Rajendran, bound by his duties to Mayil, tries to protect the henchmen. Mayil kidnaps Divya for ransom. Singam rescues her with unexpected help from
Home Minister Ramanathan. Singam successfully traces the origins of the kidnapping racket to Mayil and also gets promoted to
ACP of the specially-formed Anti-Kidnapping
Task Force. Mahalingam, who was hostile to Singam following an altercation with Soundarapandi back at Nallur, softens up and agrees to give him Kavya's hand in marriage. The entire police force, including the police commissioner and Rajendran, is now on Singam's side and helps him to fight Mayil. They manage to kill Mayil's henchmen in an encounter at a hospital and begin to target everyone and everything related to Mayil. In retribution, Mayil starts targeting everyone close to Singam, including Kavya, but is saved by Singam and Ravi, who is hacked to death by Mayil. To escape from getting arrested, Mayil kidnaps the daughter of
the Karnataka Home Minister. Mayil falsely tells Singam that he is going to
Pondicherry with her, but he is going to
Nellore in
Andhra Pradesh to put the police off the track. However, Singam manages to pursue them till
Gudur near
Nellore, where he rescues her and kills Mayil in an
encounter. Singam resigns from his job publicly in a felicitation function organised for him, where he heads back to Nallur with Kavya. Singam is stopped briefly by Ramanathan, who offers an undercover mission, to which he willingly agrees. ==Cast==