David Billa, a Sri Lankan refugee, along with several others, arrives at a camp in Rameswaram, where he befriends Ranjith. The refugee camp is constantly terrorised by corrupt police Inspector Raghubir Sinha. Billa attacks Raghubir when he tries to forcefully detain one of his friends and, in return, gets tortured in a police cell. Billa vows to make him suffer. He goes to meet his widowed sister in Chennai as she is his sole living relative, but is shunned by her due to his criminal past in Lanka. A few days later, Billa and Ranjith are hired to transport fish from Rameswaram to Chennai, which is a plot by Raghubir to trap them as the truck they are driving has diamonds inside. Police intercept them to arrest them, but Billa realizes the play and kills all the cops. Despite Ranjith advising fleeing with the Diamonds, Billa drives the truck to its destination, where they meet Hotel owner Selvaraj. Raghubir's ally Mustafa bai comes minutes later and tells him that Billa has escaped with the Diamonds. Selvaraj realizes the ploy and kills Bhai. Selvaraj is pleased with Billa's loyalty and employs him & Ranjith in his illegal business. Days later, Billa murders Raghubir in a brothel and also kills an egoistic immigration officer who had insulted him earlier.

Months later, a Goan Criminal, Kotiswara Rao, visits Selvaraj and asks for help in selling off the heroin he had brought along with him. Selvaraj refuses, but Billa volunteers to sell it off and tries to deal the heroin with a local thug who refuses to pay for it in return. In a brutal scuffle that ensues where one of Billa's friends is slaughtered, Billa kills them all and goes directly to Koti's boss Abbasi in Panaji with the money and the heroin, which is very impressed and recruits him. Abbasi is a drug trafficker and the boss of the biggest drug cartel in Goa. Abbasi is in business with powerful and dreaded Russian gun dealer, Dimitri.

When Billa and Ranjith retrieve Dmitri's arms consignment held by the Indian coastal guard, they enter his good books. Billa climbs the ladder of Abbasi's gang quickly. He learns of his elder sister's death and brings his niece Jasmine with him. He provides her with a big house and servants, and enrolls her in a medical college. Billa and Koti travel to Russia to meet Dimitri, who own a large arms and ammunition manufacturing unit. Billa meets corrupted interpol officer Jagdish in Dimitri's mansion, and is astonished by the functioning of the mafia and its international network. Billa signs a larger deal with Dimitri without Abbasi's knowledge. at the same time, Dimitri kills Bobby, Abbasi's henchman who comes with Koti and Billa as a translator. Dimitri and Jagdish then reveals that Bobby is actually a interpol spy who was really betraying Abbasi's gang. After coming back to Panaji, Koti misleads Abbasi as Billa kills Bobby and directly started business with Dimitri, which creates rivalry between Billa and Abbasi. Tensions further increase when Billa beats up Satish Kumar, son of an influential minister, Praveen Kumar, when he tries to misbehave with Jasmine in a party. Abbasi expresses his discontent and vents at him. Billa, surprised and enraged at his ingratitude, walks away with Ranjith and two others. Billa, Ranjith, and ally Ram plot to venture into the drug business on their own during the carnival. At the carnival, Billa is betrayed by Ram and is brutally attacked. However, he survives and kills the assailants, Abbasi and Ram, eventually becoming Goa's most powerful gangster. He begins a relationship with Abbasi's girlfriend, Sameera.

Dimitri arrives in Goa and finds himself in a fallout with Billa, when they try to re-negotiate a deal. Dimitri thereafter seeks to oust him, with the help of Koti, Satish, and Praveen. They proceed to assassinate Chief Minister Mohan Kanth, and the blame falls upon Billa. However, Billa is freed by Ranjith, who threatens the judge and his family. Billa rescues Jasmine from Koti's men and informs Sameera to take Jasmine to safety. But Sameera betrays Billa, informs the minister's son, who holds Billa and Jasmine captives. Billa, while being held to the ground and is mocked at by Satish, who slits Jasmine's throat. Enraged at her death, Billa overpowers and kills everyone.

Meanwhile, in Russia, Dimitri is having a meeting with the African warlords, and Koti is present with him. He shows his factory in his computer via a series of webcams, and much to everyone's shock, Billa is seen destroying his factory. He also sees his consignment train go off course. He gets angered and kills Koti for not killing Billa, and he sets out himself to finish the task. The arms factory is destroyed by Billa, Ranjith and their men. Dimitri arrives and follows his delivery train, when to his shock, the delivery train is blown by Billa, who is waiting for him on his own helicopter. After an intense battle, Billa throws Dmitri off the flying helicopter. In the epilogue, Billa and Ranjith board a plane out of the country, and Sameera, Police Officer R.K. De Silva, Billa's Lawyer and Minister Praveen Kumar are killed by Billa's assassins.