Muralipandian is the only son of Chellapandian, a disabled policeman who is now working in the State Crime Records Bureau and expresses a desire to see his son as an Inspector. However, Murali is against becoming a policeman due to an incident which happened in his childhood; when Chellapa lost his leg during police duty, his wife fell down the stairs on hearing the news, leading to her death and left a crippled Chellapa to single-handedly looking after the young Murali. His ambition is to become a Bank manager, and he manages to get an interview for the same in a bank. While on a pilgrimage, Murali meets Ambujam, a young doctor who is travelling with her chaperone, who is her grandmother Aishwarya. Ambujam initially thinks ill of Murali due to unsavoury incidents which occur between them during the journey, but after she finds out about Murali's true character as he helps her Aishwarya recover from dehydration, she falls in love with him. She expresses a distaste for marrying policemen, which impresses Murali. Meanwhile, a spate of robberies occurs in Chennai where several bank accounts through ATM machines are stolen. The robberies are led by a bank employee Shiva, assisted by a martial arts instructor Lawrence. The duo manages to avoid being caught. Murali first encounters the duo robbing an ATM while returning from the pilgrimage and breaks Lawrence's arm in a combat.

An injured Lawrence vows vengeance against Murali. Later, Murali receives a letter stating that he had been accepted at the Tamil Nadu Police Academy for police training. He reluctantly attends the training for Chellapa's sake and deliberately performs poorly during the training in the hope of getting expelled from the academy. Unfortunately, SP Nagaraj, who happens to be Ambujam's father and a former colleague of Chellapa, finds out about Murali's plan and makes a deal with him to avoid the matter reaching Chellapa's ears; If Murali performs badly during training, he will not be expelled from the academy. Instead, he will be made as an SI with the assurance that he can resign if he does not like the job after 30 days, after which he can marry Ambujam. Murali accepts, but this strains his relationship with Ambujam. Shiva and Lawrence plan to steal money from ATMs using information from international credit cards. The robbery is a success, but the CCTV cameras in two different ATMs have exposed Shiva as one of the robbers due to his height. The duo are arrested by Murali, who is now a sub-inspector, but they manage to subdue the constables and escape later that night, while Murali is out on a date with Ambujam. They encounter Chellapa, beat him up, and shoot him in his chest. Ambujam feels sorry about what happened to Chellapa and accepts Murali's decision to become a policeman.

Buoyed by Ambujam's approval and also determined to take revenge on those who shot Chellapa, Murali takes up the robbery case and assumes that the duo did not work alone, instead of having an accomplice. This proves to be true; the accomplice turns out to be a forger who made fake credit cards for the duo to steal money from the ATMs, but this evidence reaches a dead end when the accomplice reveals that he never saw the duo without their bike helmets. Murali then interrogates the security guards of ATMs in the outskirts of Chennai as he feels that the robbers would have used them to conduct their robberies since money would not be refilled in such ATMs until it runs short of cash due to lesser number of withdrawals. One of the guards interrogated turns out to be an accomplice of the robbers, providing them gadgets to assist them in the robbery. He does not know where they are. Murali decides to track the robber's phones with the intention of finding their location once someone calls them. In retribution, Shiva and Lawrence try to kill Chellapa, who is in the ICU, also kidnapping Ambujam in the process. Murali rushes to the hospital, where he sees Chellapa still alive, after which he pursues the robbers, finally encountering them on the banks of the Cooum River, where he kills Shiva and Lawrence and rescues Ambujam. Murali is later honoured by the police department for his role in thwarting the ATM robbery, in presence of Chellapa and Ambujam.