A veteran cop chases a cold blooded serial killer, who murders his victims in alphabetical order.

Chandrasekhar (Mohanlal) is an IPS officer who lives a lonely and quiet life after being divorced from his wife, Deepthi (Priyamani), a leading criminal lawyer. Things change when he is made the head of the Metro Crime Stopper Cell in Kochi, and single-handedly saves three college girls abducted by a psychologically deviant guy. Chandrasekhar gets a congratulatory note from an anonymous man calling himself "Z," who challenges Chandrasekhar to figure out how he is going to bump off one target after the other. Chandrasekhar is forced to take up the investigation of the murders, which follows a mysterious alphabetical pattern.—jst

The movie is loosely based on Agaths Christie's The ABC Murders, where the murderer signs off as ABC (like how he signs off as Z in this movie) in his letter to the detective Hercule Poirot. There is some loose similarity in the killings, as well as the alphabetical names of the victims. That is not to take away the fact that the movie has been well done.—TeshNair