In his various screenplays and films, David Ayer has shown a seemingly bottomless interest in the Los Angeles Police Department. As the writer of Training Day and the director of Street Kings (which boasted a script co-written by James Ellroy, another man who has made a career out of his obsession with the LAPD), he’s returned again and again to these boys in blue, and End of Watch continues this motif. The movie stars Jake Gyllenhaal and Michael Pena as partners Brian and Mike, beat cops who pass the time during their shifts by hurling endless insults -- often racial -- back and forth, but only because they are obviously deeply devoted to each other. Over the course of a few months, they inadvertently anger a group of high-level drug dealers, while family man Mike helps soon-to-be lawyer Brian settle down with the right girl (Anna Kendrick). Describing the plot makes the movie sound like a routine buddy-cop film, and while it certainly stays true to many of that genre’s conventions, End of Watch is actually a kick for two very different reasons. First of all, Ayer shoots the picture in a commando, first-person style that, though certainly flashy, never devolves into a frenzied mess. Early on, Ayer establishes the premise that Brian is recording their daily shifts for one of his classes, and even when he abandons this premise in later scenes, he maintains the grittiness and shaky camera work so that the whole movie has a cohesive and distinctive look. It’s one of the most stylistically gonzo mainstream films of the year. The other appealing aspect is the work of the lead actors. Gyllenhaal and Pena have such a natural chemistry together that we’re with them from the opening scene. Their offhand ease with each other is boyishly charming rather than frat-brother annoying, and their conversations often have the loose, go-nowhere vibe that was the hallmark of Seinfeld. When you combine this sensibility with the film’s hyperbolic visual style, the result turns into something like an episode of Dragnet that looks like the first five minutes of Kathryn Bigelow’s Strange Days. As unconventional as Ayer and cinematographer Roman Vasyanov’s approach is, the story itself ends up being thoroughly conventional. The picture doesn’t want to turn away from the gritty realities of being a member of the LAPD, but anyone familiar with basic storytelling structure can see how this movie must end by around the midpoint. Even with that flaw, End of Watch is so inventive, and so anchored by two highly enjoyable performances, that it makes for one of the more singular, if not entirely successful, entries in a genre that often suffers from stale sameness.