Malayalam thriller Salute turns the police procedural upside down. Rosshan Andrewss’s film, written by Bobby-Sanjay, is about a cop on the hunt – for cops.

Dulquer Salmaan plays Aravind, a member of a team of police officers led by his brother Ajith (Manoj K Jayan) that has been responsible for a cover-up. The policemen have come under intense political and public pressure to solve the murders of a couple. They plant evidence against an auto driver and send him to prison, ignoring the clues that lead to the real murderer.

Aravind is so troubled by his participation in the deception that he goes on unpaid leave. Three years after the incident, he returns home with a girlfriend (Diana Penty) and every intention to implicate his brother and former colleagues.

The SonyLiv release maintains a grip despite its length (two hours and 25 minutes) and plotting loopholes. Filmed with polish and performed with understatement by the cast, Salute is most engaging when Aravind is in investigative mode, following one bread crumb to the next. The guilt that prompted Aravind to turn against his brother turns out to be a big fat red herring. There are better and more curious films in Tamil and Malayalam about the ways in which police officers violate the law.

As a whodunit, Salute works just fine. As a whydunit, though, the film is as mysterious as its ambiguous ending.