“Killing Them Softly” is, in its own chatty and slight way, the “Unforgiven” of hit-man thrillers. It’s a gritty, riveting nuts-and-bolts-of-murder tale that vividly illustrates what it is that these much-glamorized thugs do, and the gruesome, agonizing fate of their victims.

The guys the contract killer (Brad Pitt) comes after fit this memorable “Unforgiven” quote:

“I guess they had it coming.”

But this reply is just as apt:

“We all got it coming, kid.”

The mob lawyer (Richard Jenkins) arranging all this mayhem tries to minimize the death toll, calling one target “a nice guy.” The cynical Jackie (Pitt) informs him that “They’re all nice guys.”

There was this mob-protected underground poker game that Markie (Ray Liotta) ran. Markie’s got a history of having his games robbed. And this one mug, Johnny the Squirrel (Vincent Curatola), figures a way to pull another heist and let Markie take the fall. Of course, getting ex-con Frankie (Scoot McNairy) and Frankie’s Aussie-junky pal Russell (Ben Mendelsohn) to do the deed wasn’t the smartest move.

That’s why Jackie’s been called. That, and because everybody’s favorite local hit man (Sam Shepard) is sick.

Jackie figures there’s a lot of work here, something he lays out to the lawyer in a couple of long, heart-to-heart talks. So Jackie brings in a subcontractor, New York Mickey (James Gandolfini). But Mickey’s a mess, an aggressive drunk who holes up in a hotel emptying bottles and insulting hookers. Events are going to outrun them all if Jackie doesn’t get a handle on things, tidy up.

As on “The Sopranos,” Gandolfini has the confessional role here, playing a character paranoid about what his wife will do if he’s imprisoned, a sentimental boor who is rude to one and all, but misty-eyed over past “jobs.” McNairy and Mendelsohn share scenes in which the sober one tries to wring information out of the swaggering drug addict from Down Under, whose point of view is mimicked by a series of blurred images, slowed-down conversation and blackouts. Guys this nervous may be able to steel themselves, briefly, for the robbery. The consequences of that are still going to make them weepy little girls.

Pitt dials Jackie down a few notches, keeping the guy as realistic as the movie around him. This isn’t “Seven Psychopaths” — murder and those who commit murder (played for laughs). Jackie’s encounters with associates, subordinates and victims all have a nervous edge about them. We can guess what he’s capable of. He’s not sadistic, not interested in making someone suffer. But he’s also not sentimental, and not fond of those who wail for their mama and wet their pants when he draws down on them. He’d rather “kill them softly, from a distance.”

That “distance” is not a copout writer-director Andrew Dominik (working from a George V. Higgins novel) stumbles into. These characters are, to a one, lowlifes, the sort who’d steal a tip off a diner table. The deaths here are gory, gurgly and depressingly real. With so many inexplicably sympathetic movies about hit men, it’s hard to remember one that made even sketched-even victims worth mourning.

But where Dominik and Pitt’s previous movie together (“The Assassination of Jesse James by the Coward Robert Ford”) was daguerreotype slow and stately, “Softly” is slow and freighted with obscure meaning. Dominik labored over the soundtrack, stuffing in vintage records, TV news clips and talking-head chatter about the 2007-08 economic meltdown and the presidential election that followed. So, the “real criminals” get away with this sort of thing? “Hope” and “Change” are gossamer promises, because there are always guys like Jackie to clean up a mess filled with Wall Street types who “have it coming”?

That leaves “Killing Them Softly” with just a hint of the under-developed, a big metaphor not quite digested. But that doesn’t obscure the fine, flinty performances and unflinching realism of the one hit-man thriller among many to not seem redundant, worshipful and glamorous.