Deva (Suriya) arrives at the Chennai International Airport after running an errand for Arumuga Dass (Prabhu Ganesan) of smuggling pre-release unlicensed movies on DVD. The two leave for their hideout and instruct Dilli (Karunas), a hearing-impaired assistant of Dass, to make copies of the DVD. Just when police crews arrive into their vicinity, Dass informs Deva and the rest to leave. Deva tells the others to leave while he quickly sets up the burning process. Deva also leaves the hideout just in time. However, the police officers arrive at the hideout, only to see the burning process of the DVDs complete. The police then seize the DVDs and computers. The inspector, who was a friend of Dass, tells him that he can close the case if one of Dass’s men agrees to the crime. Deva attempts to go, but another man, Chitti (Jagan), who had no affiliation to them volunteers, takes the blame. Later, Chitti joins Dass’s group and befriends Deva.
Dass is a diamond trafficker who smuggles diamonds from Africa. Deva’s mother Kaveri (Renuka) does not appreciate his affairs with Dass, as she wants Deva, who holds a Master of Science degree, to have a government job. He occasionally visits home and her roadside grocery shop, only to get scoldings from his loving mother. When Deva is invited to Chitti’s house, he gets impatient and knocks on the door. As the door opens, Deva slips and falls on the bed, expecting to see Chitti but scaring his younger sister Yamuna (Tamannaah) instead. Just before he drives off, he curses himself for making such a stupid mistake. Yamuna catches this and accepts his apologies, then they slowly fall in love, their relationship is accepted by Chitti . Meanwhile, Kamalesh (Akashdeep Saighal), the arch-enemy and competitor in smuggling of Dass slowly starts to try to foil Dass and his employees. A prank phone call from Chitti leads to a near-death experience for Deva and Kaveri. Escaping alive and outraged, Deva goes and confronts Chitti, releasing his anger to the full extent. Chitti then reveals that he was Kamalesh’s personal spy and that even though that their bosses were foes, he was happy to be a friend of Deva. Disgusted, he leaves and Chitti too, and at that moment, Yamuna arrives, hearing everything. Thus, this stir of events causes the interval of the movie.
After these events, Deva and Yamuna break up. In Malaysia, under circumstances, Chitti and Deva meet. Chitti, who was fed with drugs fall prey to them and starts reacting. In a last attempt to rekindle their friendship, Deva attempts to save him. Chitti then explains that it was wrong of him to be a spy, but still admits that he was lucky to have him as a friend. He dies when Kamalesh’s henchmen try to salvage the drugs by cutting him open. Heartbroken, Deva returns to India.
When he arrives, Yamuna approaches him and asks the police officers to arrest him. But she notices Chitti’s phone which he recorded a video before dying, brings it out, which contains a recording how Chitti died, also she sent the video to Dass. It is here clear that Deva didn’t kill him, but hid from Kamalesh’s henchmen. Yamuna apologises to Deva and the two come together again. Then later circumstances force Deva to become a part of the security squad in the airport as he is accused by Parthiban (Ponvannan), Assistant Commissioner of Income Tax Air Intelligence Unit of carrying drugs. He denies it, saying that the packet of drugs was given by a passenger’s relative as she had forgotten it. The drugs are opened and it is found that Heroin is sealed in them. Deva then realises and explains that huge amount of drugs are being transported by distracting him with a small amount. The flight is delayed and all passengers are asked to take food from the canteen. There are a few who don’t do so, and hence their stomach is X-Rayed and a huge packet of heroin is found. Then Deva is asked to help Parthiban and the Customs for arresting Kamalesh.
Deva and Parthiban put a cab like room outside Kamalesh’s house and with Yamuna’s help, a transmitter is put in Kamalesh’s study. Then, all his conversations with his clients are recorded but Kamalesh later finds out and attempts to kill them, which fails. He later finds out that idols made of heroin are compressed under high pressure to disguise their smell and properties. With this evidence, the Income Tax comes to raid Kamalesh’s house but he acts quickly and removes all the stuff. During a final attempt to arrest Kamalesh, the truth is forced out of his accountant but Kamalesh kills him to avoid any witnesses. Later, Deva’s house is almost burnt and Dass is killed by Kamalesh, which infuriates Deva. He is then forced to go to Africa and confront Kamalesh.
When he returns to India, he is again inspected by the Custom Officer. Deva learns that it was his mother this time who exposed his smuggling mission. He has no choice but to surrender the diamonds, and so he does. Parthiban hands Deva to sign a form, which Deva hesitates. He then learns that is a government security job application form. Parthiban says that Deva’s criminal mind is required for such a job in the Customs. He then asks what had happened to Kamalesh to which Deva replies that he had gone to Congo to strike a business deal. Then a flashback shows that when Kamalesh was returning from stealing the diamonds, his gang is killed by Deva and he is pushed off the cliff. The film ends on a happy note as Deva leaves the airport with his mother and Yamuna.