A tough debate occurs within an Andhra Pradesh state assembly about the long pending murder case of Visakhapatnam City Police Commissioner Ramakrishna. The Home Minister of Andhra Pradesh proposes recruiting Singam from Tamil Nadu to Vizag as the new DCP, by order under the CBI. As Singam arrives in Vizag station, he fends off an attack from goon Gun Ravi, who works for Vizag's most influential and powerful don Madhusudhana Reddy. Singam starts to behave as a corrupt cop and secretly investigates the murder of commissioner.

Singam is followed by Vidya, a journalist in guise of a student hoping to write a story on Singam. Singam had previously covered his relationship with his wife Kavya Mahalingam to keep her away from enemies, and after curiosity from Constable Veeram, he closes it as a divorce, revealing it only to Inspector Subba Rao. After briefly confronting Bheemli Selvam, Reddy's man who ordered the attack at the train station, Singam finds that a constable at the station has gotten sick from consuming an expired medicine tablet. With help from a paroled hacker named Murali, Singam tracks Mallaiya who drove Ramakrishna to Vizag harbour on the night of the murder.

A local schoolteacher informs Singam that a toxic smoke attack from the nearby dump killed his 32 students, including his grandchildren. Singam realizes that Ramakrishna intended to expose illegal dumping of mediwaste and electronic waste, which included recycled tablets being sold to the public and the smoke attack on the school. The garbage is being imported by Vizag Scraps owner Rajeev Krishna in exchange for free metal scrap delivery to steel companies in Australia. Mallaiya confirms that Reddy, who authorizes this business in India killed Ramakrishna to prevent him from thwarting his operation.

Reddy and Rajeev's activities are supervised by wealthy, powerful and corrupt current Commercial Minister of Australia and Businessman, Vittal Prasad, who receives full support from his father, Union Minister Ram Prasad. In the meantime, Vidya writes an article on Singam claiming that he exported Reddy for personal gain and that he is corrupt, putting Singam's reputation at edge. As a result, he has Vidya arrested and fined for discrediting him. Singam begins to eliminate and arrest criminals all over the city, including Selvam whom he guns down. Later, Singam heads to Vizag harbour to obtain evidence from Reddy's containers but is attacked by his men while Ravi murders the school teacher.

Vittal calls Singam anonymously and threatens to use his influence to kill Singam's family if he doesn't stand down. The next day, Singam chases down Ravi and arrests Reddy. He pays a personal visit to Vittal in Australia from looking into Reddy's contacts, and confirms that he is the one behind the illegal dumping. He narrowly escapes Vittal and returns to India, where he finds that Reddy has been bailed by three criminals, who framed the Commissioner for supposed assault on one of their wives, and justify the murder as vengeance. Singam is also fired from the CBI for speaking out of turn, but has the home minister transfer him as a Andhra pradesh cop in Vizag to continue pursuing Reddy's men.

Singam exposes the garbage containers to the public, forcing Vittal to come to Vizag. When Vittal warns him again to stay out of his way, Singam responds by having Subbu Rao kill Reddy, whom previously killed his nine-year-old son in a city riot to defend Ram Prasad's position. Singam brings Vittal to his station and gives him another chance to repent for whom he's hurt. Singam and Kavya later visit Thoothukudi to attend Kavya's grandma's funeral. They are followed by Rajeev, who is arrested. When Vidya attempts to interview Vittal, she is captured and drugged. With help from Murali, Singam rescues Vidya but is targeted by Vittal's men who bombs the police station.

Singam decides to finish this once and for all and gets an arrest warrant for Vittal using computer evidence of agreements signed with medical companies, hacked by Murali. The next day, Singam pursues Vittal all the way to Hyderabad Airport in Telangana and has him arrested. Vittal escapes custody into a nearby forest, where Singam catches him and after a long fight, Vittal dies there. Singam regains his post and respect while Ram Prasad is removed from cabinet position for assisting his son. Kavya is revealed to be 6 months pregnant and Vidya severs contact with Singam after getting engaged to a good prospect. Singam receives a call from Home Minister Ramanathan, who calls him for another mission.