I’m not sure who appointed David Ayer poet laureate for the LAPD, but at least he takes the job seriously; along with the usual mean-streets bluster and brutality, his cop-thriller screenplays (Training Day, Dark Blue) conscientiously record the hardening effects of a thankless and frequently pointless job. This story of two patrolmen in South Central (Jake Gyllenhaal and Michael Peña) turns on a first-person gimmick—as part of an amateur filmmaking project, the characters wear micro-cameras on their shirts as they roll—and though Ayer, directing his third feature, drops the conceit whenever it’s inconvenient, it enables him to fashion a consistently gripping tale without resorting to Hollywood plot mechanics. In fact, there’s very little plot here at all, just an alternating current of patrol-car comedy and nightmarish emergency calls that require the heroes to plunge blindly into dangerous situations, until they stumble onto one that offers no escape.