The story begins with an animated interpretation based on the classical Indian mythology of King Vikramadithyan and Vedhalam. The influences from this traditional mythology correlates with the story of a police inspector, Vikram (R. Madhavan), (who is brave, honest and draconian about right and wrong) and a dreaded crime lord, Vedha (Vijay Sethupathi), (who is wise and seems to understand the grey shades between good and bad) in the present era. Vikram and his colleague Simon (Prem) are part of an ‘encounter’ unit led by the latter, formed to eliminate the dreaded crime lord, Vedha (Vijay Sethupathi). On one such encounter, the squad kills a few gangsters, framing the death of an unarmed criminal to avoid further inquiry. When a new recruit, Santhanam (Manikandan) is nervous about this, Vikram calms him by saying that he sleeps peacefully at night despite the encounters because he knows that the men he shoots are criminals, and not innocent. The unit makes plans for another raid when, Vedha walks into the police station and surrenders.
Vedha is totally imperious to intimidation and does not acknowledge the police officers until Vikram walks into the interrogation room. Vedha cheekily offers to tell him a story but Vikram, who believes that all evil must be severely punished, shows no interest. Vedha asks Vikram to only listen and then adjudge what is evil and what is not.
Vedha’s first story is about how he, a henchman in a cocaine smuggling gang, endeared himself to the boss, Cheta (Hareesh Peradi), and eventually rose to become a gangster and smuggler himself. Vedha actively dissuades his intelligent brother, Pulli, to stay away from crime. However, he is forced by a rival gangster, Ravi (Vivek Prasanna) to carry drugs. When Pulli is caught by the police; he confesses and Ravi is arrested. Under his boss’s orders, Ravi assaults Pulli, which leaves a permanent mark in his hand. Vedha asks Vikram if Vedha should kill Ravi who committed the act or his boss who gave the order. Vikram replies that Ravi was merely an instrument; the boss was the real culprit. Vedha replies that he did kill the boss. At this point Vedha’s lawyer intervenes and Vedha is bailed out. Vikram is stunned to find out that Vedha is represented by his wife, Priya (Shraddha Srinath).
Vikram realises that unarmed person shot in the last encounter was Pulli, based on a scar in his hand. Vikram assumes Vedha might try to kill Simon, as Simon is instigator of the encounter. Vikram rushes to save Simon only to find him shot and killed by Chandra (Varalaxmi Sarathkumar), Pulli’s girlfriend, who has also been killed. The Superintendent of Police (Achyuth Kumar), head of the encounter unit, puts it down as a botched encounter and closes the case. Priya refuses to divulge Vedha’s whereabouts to Vikram, which tests their marriage. Shocked and angry, Vikram raids Vedha’s tenements, captures him and brings him into the woods to shoot him, when Vedha pleads with Vikram to listen to another story, as his last wish, which may reveal something about Simon’s death.
The second story starts with Pulli, now grown up, offering to launder Vedha’s ill-gotten income by investing it in shares. Vedha’s boss, Cheta invests five million rupees into this venture. One day Chandra is supposedly kidnapped and the money is missing. Chandra later returns and reveals that she had stolen the money to start a new life, away from the tenements and crime, but her love for Pulli brought her back to him. Vedha returns the money to Cheta, but is ordered to kill Chandra for betraying Cheta in the first place. Vedha now asks Vikram if he should respect his boss and carry out the order or if he should follow his heart and disobey Cheta, an action that would escalate into an all-out gang war. Vikram replies that he should support Pulli as he is innocent and oppose Cheta, to which Vedha agrees. Vikram stumbles for a moment when he realizes that Pulli was innocent. In that moment, Vedha attacks Vikram and flees, after telling him to investigate Simon’s and Pulli’s deaths.
A troubled Vikram starts investigating Pulli’s death. He recalls that Vedha opposed Cheta and managed to get Pulli and Chandra out of the city, and wonders why Pulli was present at the site of the encounter. He also notices that Chandra was tortured prior to her death. Vikram finally discovers that Ravi, once Vedha’s underling, was behind the initial shootout which, to Ravi’s advantage, would have decimated Vedha’s stronghold. Vikram informs Vedha, who tracks Ravi down and brings him to an abandoned factory. Vikram arrives to find Ravi, beaten within an inch of his life. Vedha proceeds to tell Vikram the third and final story.
Vedha had sent Pulli and Chandra to Mumbai away from Cheta. Vedha begins to notice a surprising pattern: only his men are being systematically targeted and eliminated by the police. Vedha himself narrowly manages to escape when his friend sacrifices his life for him. Based on Ravi’s confession, Vedha narrates that Simon was paid by Ravi to gun down his men. Vedha asks Vikram if Simon was in the right; since he became corrupt to get the money to pay for an expensive medical procedure for his young son, and Vedha’s men were gangsters who deserved to die anyway. Vedha then kills Ravi and escapes before Vikram can answer.
The encounter unit arrives and castigates Vikram for letting Vedha escape again. Vikram slowly pieces everything together. The entire unit had come into sudden money which could only be traced back to Ravi. The SP reveals that Ravi had paid them to kill Vedha and Chandra’s abduction was intended to get Pulli from Mumbai, which would then lure Vedha out of hiding. The guilt-ridden Simon had arrived early that night to save Chandra, not to kill her, but they were both killed, and their deaths covered up. At this point when the unit prepares to kill Vikram, Vedha appears again and saves him. A gunfight ensues, where Vikram shoots and disables his colleagues, who were mere instruments but kills the SP, the instigator. Vedha, who had acquired a firearm turns on Vikram to find Vikram has a gun on him. Vikram asks Vedha if he should let Vedha go for saving his life or kill him since he is a criminal. The film ends with the standoff between the two men.