David Billa (Ajith Kumar), a Sri Lankan refugee along with several others, arrives to the camp in Rameswaram where he befriends Ranjith (Yog Japee). The refugee camp is constantly terrorised by corrupt police officer Raghubir Sinha (Krishna Kumar). Billa attacks Raghubir when he tries to forcefully detain one of his friends and for revenge he gets Billa tortured in police cell and vows to make him suffer. A few days later, Billa and Ranjith are hired to transport fish from Rameswaram to Chennai. But unknown to them, it was a plot by Raghubir to trap them as the truck they were driving had diamonds inside. But Billa realises the ploy and kills all the cops and drives the truck to its destination where they meet Selvaraj (Ilavarasu), who is pleased by Billa's loyalty and includes him in his business. Billa murders Raghubir at a brothel.
Kotiswara Rao (Manoj K. Jayan) visits Selvaraj and asks him if he could help in selling off the heroin he had brought along with him. Billa volunteers to sell it off and tries to deal the heroin to 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 (Sudhanshu Pandey) with the money and the heroin, who is very impressed by the former and recruits him. Abbasi is in business with Barovian mafia led by Dimitri (Vidyut Jammwal), who tells him that his arms consignment has been held by the Indian coastal guard and he asks for his help. Billa and Ranjith agree to retrieve the consignment for him and are congratulated by Dimitri for their work.