Brendan Gleeson (also from In Bruges) stars as Sergeant Gerry Boyle, a bored cop in a tiny Irish burg named Galway, where very little crime actually occurs. To pass the time, Boyle spends time visiting his mother, picking up hookers, and occasionally saying a thing or two just to get a rise out of any of the numerous stiffs surrounding him. The newest stiff, an American FBI agent named Wendell Everett (Don Cheadle), has been reluctantly teamed with Gerry in hopes of stopping a "half-million" dollar drug delivery organized by a gangster named Sheehy (Liam Cunningham), and the results are...acidic.

At a glance, Boyle seems like a real ass; he's loud and straight-to-the-point, some of his jokes are casually racist, and he seems less than overwhelmingly concerned with the impending drug deal and at least one homicide stemming from it. Upon closer investigation, however, there's a devilish smirk and relatively straight moral compass guiding Gerry's actions. If he says something to get a rise out of Wendell, no matter how outrageous it is, he does it both to see how his new partner reacts, and in many ways, as a way to locate their common ground. To that end, Gleeson imbues Gerry with hidden layers of sharp intelligence, self-awareness, and ultimately, a genuine kind-heartedness that shows through around the character's rougher edges.

On the other side of the table, Cheadle's character of Everett is a guy who's not aware of himself until Gerry uses his personality to point it out to him, and Cheadle does a good job of playing his slow-burn shift from responding to Gerry's barbs on the surface to reflexively understanding that Gerry's ribbing is observant, in a backwards sort of way. The two's on-again, off-again level of growing respect drives the whole movie, as Gerry slowly gets Wendell to look at the situation the way he looks at it; early scenes of Gleeson without his co-star are far more broad and a little clunky. Meanwhile, Mark Strong gets his best role to date as one of Sheehy's fellow gangsters, who bristles at having to deal with idiots in the crime business and argues with Sheehy and company about philosophy, and Cunningham himself has a great scene with Gleeson in a diner that may contain the funniest exchange in the movie.

Compared to Martin, John's direction loses some of the glossy sheen, opting for a more naturalistic, less cinematic look befitting the film's small-town story. He also opts for a far brighter ending than his brother, which ties all of the movie's threads together in a remarkably satisfying way. The Guard may not fit into the "buddy cop" genre, which is all about surface differences, but plays off of it in a pleasing way. Where some movies start with a growing friendship that ultimately turns into professional respect when they realize their goals are aligned, McDonagh does the opposite, turning a begrudging professional respect into an unorthodox friendship that neither of the two men would've guessed they wanted.