Nerve-rattling in the best way, the sharp, visceral urban police procedural End of Watch is one of the best American cop movies I've seen in a long time.

Ultimately, the mock-doc device works because Gyllenhaal and Pena so completely reinvent themselves in-character. Instead of wearing the roles like costumes or uniforms, they let the job seep into their skin, a feat without which "End of Watch's" pseudo-reality never would have worked.

Easily one of the year's best films and one of the best ever in the well-worn cop genre.

The action and the chemistry is stronger than the story, because Gyllenhaal and Peña are good. In that respect End of Watch works better as a series of vignettes held together somewhat loosely by a larger story.

As social insight, End of Watch is useless, but as engrossing entertainment, it's irresistible, thanks to Ayer's gift for dialogue, the relentless pacing set by film editor Dody Dorn, and gorgeous performances by Gyllenhaal and Peña.