Jake Gyllenhaal has already proved his serious acting chops many times before, most notably in “Jarhead” and “Brokeback Mountain,” but it’s been a while since he found a vehicle that would not just showcase his talent but be worthy of it.  “End of Watch” is a return to form; Gyllenhaal and Michael Peña give fantastic performances in this wonderful, tense, suspenseful cop drama.

Brian (Gyllenhaal) and Mike (Peña) serve as cops in South Central Los Angeles, the city’s toughest neighborhood. They frequently find themselves in terrifying situations, which we’re never quite sure they’ll survive. Though their unnecessary roughness borders on brutality, the sympathy the movie draws towards both the cops’ and criminals’ dire situations and constrained hostility blurs the line of moral rectitude. It’s all filmed in handheld, rough and at times grainy shots, and the effort to keep the film gritty just misses an aesthetic cop-out.

The heart of the film lies in the strong and authentic friendship between Brian and Mike. Much of the film happens in their patrol car, where we listen in on their daily conversations. Brian’s stifled racism comes out when, assuming a Latino accent, he mocks the endless stream of family quinceañeras that Mike attends every weekend, but the trust between them eases the tension into harmless fun. And Mike, a happily married man, is an endless source of good if unsolicited relationship advice for the single Brian.

David Ayer, who wrote and directed the film, succeeds in creating simple nuanced scenes or seemingly offhand lines of dialogue that speak volumes about the characters and their relationship to one another. After Brian tells Mike that he’s looking for a woman he can have a conversation with, we suspect that Janet (Anna Kendrick) might be the one, based on the cute and clever video she makes on Brian’s camera while he’s asleep. We learn everything we need to know about their sweet, loving and caring relationship by watching them sing along to a song on the radio while driving to a weekend getaway and witnessing the silly dance they do together at their wedding.

There is just enough plot to maintain the suspense, but this is really a character-driven movie. As Brian, Gyllenhaal transforms himself completely; his walk, his vocal patterns, his posture and the sense of his personal space are all very specific and unlike anything we’ve ever seen him do before. Brian is confident, cocky and smart but uneducated, and Gyllenhaal puts on a great tough-guy face for Brian while also letting us see his sensitivity and vulnerability. As Mike, Peña is equally compelling; he’s a relaxed, sweet but brave man, and we get a deep sense of his devotion to both his wife and his partner and his awareness of the dangers of his job. Both performances are precise and very realistic, and together they are dynamite. The two men have the recognizable intimacy and playfulness of close friends and colleagues. It’s a rare treat to have great character studies served up in an entertaining and gritty film about the tough work of police officers that never loses momentum.