Inspector Viktor, an eagle-eyed police officer who has been going through a personal crisis, is assigned to investigate the homicide of Nivetha, a young, unmarried woman.
Viktor questions the victim's lover, Prabhakaran. He also finds a video recording on Nivetha's phone which leads him to a Thirukural couplet.
The second victim is identified as Krishnamoorthy, an architect. Viktor gets a vital clue on the killer as he investigates further.
Previously, Viktor and his wife, Geetha, are seen having a heated argument that gets violent. At present, Viktor scours the city police records for killings in the past that match with the killer's MO.
The news about the serial killer is leaked to the press. Later, Viktor gets a cryptic warning from the killer before he can save his next victim.
Viktor and Kishore meet Prabhakaran's wife and Keerthana's friend, amongst others. They get a lead on a red-coloured car that may belong to the killer.
Viktor and Kishore question possible suspects based on the killer's car details. Viktor also gets a surprise lead from the victims' phone-call histories.
The police squad under Viktor spy on the killer, round the clock. Viktor also breaks into the killer's house and stumbles upon his personal diary.
On the speculated day of his next killing, the alarmed killer and a resolute Viktor engage in a series of mind games that can have only one winner.
