Suruli is a gangster from Madurai who runs a parotta restaurant. Due to his thug-like behaviour, he is unable to find a bride and even when his marriage is fixed, the bride runs away when she finds out about his criminal background. His notoriety comes to the attention of an Englishman named John, who is a right-hand man of a London-based white supremacist don named Peter Sprott. John offers £200,000 per week to Suruli if he works for Peter against a rival don Sivadoss, who is Peter's arch-nemesis and has considerable influence among London's Tamil-speaking population. Suruli accepts the offer with the intention to use the money to eventually settle down and give up his criminal activities, and leaves for London where he learns more about Sivadoss and his gang as well as their activities which involve smuggling weapons from conflict-ridden countries in exchange for money.

Peter's gang, led by Suruli and John, raid Sivadoss's boat yard where the smuggling is in process under Sivadoss's right-hand man Rajan. During the raid, Suruli kills Rajan as well. Sivadoss and his gang realise that Suruli is responsible for killing Rajan and kidnap him. Suruli and Sivadoss negotiate to kill Peter under the ruse of inviting him for a "peace talk" to end their feud, in exchange for £600,000 as well as a parotta restaurant in London, but during the "peace talk", Suruli betrays Sivadoss and hands over an aruval to Peter, who uses it to hack Sivadoss to death. As a reward for Sivadoss's death, Peter offers Suruli a designated area in London to start his business and allow Tamils to live there, and christens the area Little Madurai. Meanwhile, Suruli falls in love with Attila, a Sri Lankan Tamil singer. When he initially approaches Attila, she reveals that she is a widow with a seven-year-old son named Dheeran.

However, she soon reciprocates Suruli's feelings. While on a date at a park, they are attacked by Sivadoss's remaining henchmen Deepan and Dharani, who have sworn to take revenge on Suruli for betraying and helping Peter to kill Sivadoss. Deepan shoots Suruli, leaving him critically wounded. However, he soon manages to recover under Attila's care. But one day, he captures her after she injects a mysterious drug into his drip bag with the intention to kill him. When confronted, Attila reveals why she wants to kill him. Attila, Dheeran and Attila's brother are the only survivors of an aerial attack on their village in Sri Lanka during the Sri Lankan Civil War. It is also revealed that Dheeran is not Attila's son, but her brother's son. At a refugee camp, they are convinced by Sivadoss's aide to join Sivadoss's gang, who would help them move to London under the guise of husband, wife and child and are offered fake passports.

On the way, Attila's brother is caught and thrown into Peter's private prison, which is used to hold refugees and illegal immigrants, but Attila and Dheeran safely make it to London. Attila further reveals that Sivadoss was involved in smuggling with the intention to use the money to help the illegal immigrants and refugees from all countries financially and legally, and was planning to fight for her brother's release as well. Sivadoss, on hearing about Suruli's love for Attila, decided to offer him protection and get him married to Attila. But due to Sivadoss's death, the money to fight for the immigrants' rights had dried up, and Attila's brother has no chance of being released from prison as a result. Hence, Attila had planned the encounter in the park between Suruli, Deepan and Dharani with the intention to kill Suruli, but she still saved him due to her love for him.

Suruli also learns about a bill pending in the British parliament called BICORE, whose purpose is for restricting immigration and is being pushed by Peter and a few other lawmakers. If passed, most of the refugees and illegal immigrants would be deported or thrown into prisons, which would benefit Peter. On hearing this, Suruli has a change of heart and decides to help Attila, Deepan and Dharani in their fight against Peter and BICORE. With the help of Deepan and Dharani, he manages to recover the money which Sivadoss had acquired for the immigrants, and this money is used to release some of the immigrants, including Attila's brother. Suruli and Attila resume their relationship.

Meanwhile, Peter asks Suruli to travel to Birmingham to kill Andrews, a minister who is against BICORE. Suruli realises that Peter wants him to kill Andrews so that his death can be blamed on an immigrant, and thus BICORE would gain more support and be passed in Parliament. He refuses to kill Andrews. In retribution, Peter, John and their men attack Little Madurai and, in the process, kill Suruli's close friend Murugesan. With no other option, Suruli's accepts Peter's demands and leaves for Birmingham. However, during the journey, Suruli, Deepan and Dharani kill John and head for Peter's mansion instead. They manage to shoot down Peter's goons and barge into Peter's room. Despite Deepan and Dharani wanting to kill Peter, Suruli decides against it and instead transports Peter to a remote land on the Afghanistan–Iran border. Suruli, Deepan and Dharani then destroy all proof of Peter's British citizenship, offer him a fake passport from the "Republic of Mattuthavani", and leave him there to live as a stateless refugee forever.