Paramasivan movie revolves around Subramania Siva Ajith Kumar) who is sentenced to death for killing six policemen who were responsible for the murder of his father and sister. The Jailor, a Doctor, the DGP and the SP bring him out of jail to track down 15 Pak militants.
SP of Police, Nethiadi Nandakumar (Prakash Raj) is an honest, fearless and upright police officer who has been given the mission to flush out the terrorist outfit behind the Coimbatore blasts.
He decides to employ unconventional methods to fulfill his mission and engages Siva to assist him, renaming him Paramasivan, and giving him a single point agenda – trace out and erase the persons responsible for the Coimbatore blasts. Unaware to Paramasivam, Nandakumar intends on killing him after the mission is completed.
The fly in the ointment is played by Nair (Jayaram) who is a CBI offcer and who is out to trace Paramasivan and stop his unlawful activities. Who wins this entertaining race is the story of the rest.