I saw the trailer for the movie and the plot seems so obvious one cop loses his partner and seeks revenge on the perps who did it. He breaks all the rules to avenge his partner's death or is corrupt himself and brings in a new rookie who has a conscience. Which in the end the rookie brings him down or shoots and kills him in self defense.

Am I close to being right? (without spoiling it for me and others)

"He who fights with monsters should look at it that he himself does not become a monster... when you gaze long into the abyss the abyss also gazes into you..."