Vettaitan story revolves around police officers who are encounter specialists and Human Rights Commission and who is at right in delivering justice to innocent people by punishing criminals. Kanyakumari SP Ajith, a seasoned encounter specialist, believes in swift justice, dispensing it with his gun rather than relying on the courts. His methods clash with DGP Satyadev, the head of the Human Rights Commission, who champions a more measured approach, advocating "Justice Delayed is Justice Delivered" over Ajith's "Justice Hurried is Justice Buried."Ajith is called in to investigate the brutal rape and murder of teacher Saranya in Chennai, vowing to bring the perpetrator to justice within 48 hours. As he delves deeper into the case, he faces resistance from DGP Srinivas, who favors a more conventional investigation. He also encounters SP Harish Kumar, ASP Roopa Kiran, Patrick, Nazeema, and Thara, each with their own motivations and secrets. Their paths converge, leading Ajith to a chilling connection with NAT Academy Chairman Natraj, a figure shrouded in mystery.