Aarumugam (Suriya) is a thug and dealmaker with a band of boys handpicked from the slums of Chennai. Aaru was just a child when his parents passed away on different occasions. Being an orphan, he was brought up by Vishwanathan's (Ashish Vidyarthi) wife. Aaru is very devoted to Vishwanathan, whom he respects as his brother, and is ready to go miles for keeping him the most powerful person in Chennai. Vishwanathan protects Aaru because the latter gives him the violent undercover that he needs. When Vishwanathan declares war on his bitter rival Reddy (Jaya Prakash Reddy), Aaru assists him. In the process, he is attacked by Reddy's goons, but he overpowers this attempt. Things were going on smoothly when Aaru has to help Vishwanathan on an errand in protecting a girl from being dragged into a hit-and-run case. This is where he meets Mahalakshmi (Trisha Krishnan). Later on, Mahalakshmi puts forward her proposal, which Aaru declines, and slaps her. Aaru understands this and goes out to invite her to his life. Meanwhile, Vishwanathan plots to kill Aaru's friends during a protest which was oragnised by him. Aaru smells something fishy about this event and is misguided by Vishwanathan that Reddy is behind the mishap. Aaru sets out to kill Reddy and finds out that he was betrayed by Vishwanathan. Aaru realizes Vishwanathan's true, evil nature and vows to destroy his power. Aaru carefully takes out Vishwanathan's two brothers. In the climax, Aaru is seen traveling out of Chennai with Mahalakshmi without anyone knowing his location.