Picking up from the prequel, the film starts off with Maariappan alias Maari (Dhanush) as the fun-loving gangster with his sidekick Sani (Robo Shankar) and Adithangi(Punching Bag). He is chased around by ‘Araathu’ Anandi (Sai Pallavi) who is head over heels in love with him. However, try as she might, Maari doesn’t give her a second glance and constantly shows his annoyance to her.
In a parallel storyline, Gangadhar Beeja (Tovino Thomas) is shown to have escaped from jail with the cell walls scrawled with the words ‘Kill Maari’ . He is out for revenge as his brother (Vincent Asokan), who was a lawyer, promised to get Beeja released from jail. Unfortunately, his brother is killed at the hands of Maari as he tried to molest a girl, who turned out to be Anandi’s elder sister. This is also the reason why Anandi loves Maari.
Maari gets his 100th murder attempt on his life by his rival Singayya and to celebrate, Kalai (Krishna Kulasekaran), Sani and Adithangi throw him a party. While coming back, Maari gets attacked and Anandi takes him to the hospital and takes care of him.
Kalai’s brother Vallavan is shown to be hand in glove with Singayya, who has formed an alliance with Beeja to overthrow Maari. As per Beeja’s plan, Vallavan asks Sani to send Anandi for a job, which turns out to be drug smuggling, a job which Maari hates. Anandi goes to do the job and gets caught by Kalai. On confronting Anandi, she tells him that Maari asked her to do it. This sparks a doubt in Kalai’s mind.
Vallavan is caught by Maari carrying the drugs and when Maari confronts Kalai, a fight erupts. Maari and his sidekicks set fire to all the drugs and Beeja kills Vallavan, to make it look as if Maari killed him. Kalai gets enraged and orders his men to kill Maari. Maari is injured in the battle and Beeja reveals himself as the perpetrator. Beeja then shoots Maari, but he is saved by Anandi, who took the bullet for him.
The new collector, Vijaya Chamundeshwari (Varalaxmi Sarathkumar) is out to restore order and stop all gang violence. Maari goes into hiding with Anandi, whose legs are paralyzed. Eight years pass and Beeja has become the MLA candidate, by threatening Kalai. Vijaya, in an effort to find Maari, posts his picture along with Anandi’s on newspapers. Maari sees this and meets Vijaya, requesting her to remove the photos. Maari then reveals that he was living in Tenkasi with an elderly couple. Anandi got pregnant and a baby boy was born. However, due to complications by the paralysis, Anandi dies. Maari then raises the boy, called Kaali with help from the couple and Sani. Kaali is shown to have inherited his father’s behavior and keeps picking fights in school. Maari then requests Vijaya to stop coming after him (as a request) and says he changed his ways.
When Kaali sees some students in the older grade teasing a teacher, he complains to the principal. In retribution, the boys chase him and try to teach him a lesson, only to get beaten black and blue by Kaali. The counsellor, one of the boys’ father, calls Kaali but Maari goes and begs for forgiveness.
Meanwhile, the commissioner (Aadukalam Naren) mentions to the media that there is an informer within Beeja’s gang. Using his moles in the police department, Beeja tries to figure out who the mole is, but fails. It is then revealed that there wasn’t any mole and the whole story was fabricated to identify the corrupt policemen in the department, including the commissioner. It is also revealed that despite begging for forgiveness, the counsellor insisted on his son beating up Kaali and so, Maari beats up the counsellor and his henchmen. In a final encounter, Maari fights Beeja and paralyzes his legs, for revenge for Anandi. He is then shown with his sidekicks back to his old ways.