Director S. Craig Zahler's third film is as gritty as you expect, down to its morally twisted heroes.

Call it Cop Privilege. 

Arrest enough thugs, and society owes you much more than your cop salary. It’s what Mel Gibson’s character swears by in “Dragged Across Concrete.”

Yes, we’re back in director S. Craig Zahler’s world. The men are morally tortured, the dialogue packs a satisfying snap and the scenes play out in excruciating fashion. You’d swear the film’s editor fell asleep and woke up to discover that 159 minute running time.

There’s always a method to Zahler’s madness, even if “Concrete” is the least of his three singular films.

Always.

dragged across concrete vaugh gibson

Vince Vaughn and Mel Gibson play cops caught on video abusing a perp in ‘Dragged Across Concrete.’

The “Bone Tomahawk” auteur starts with characters you’ll instantly want to dismiss, if not outright hate. Gibson’s Brett Ridgeman is almost 60 but still lives cop paycheck to cop paycheck. Brett doesn’t care if he abuses a suspect or swaps politically incorrect tales with his younger partner Tony Lurasetti (Vince Vaughn).

They’re good at what they do. Correct that. They’re great at it.

When one of their uglier collars gets caught on video they’re suspended for six long weeks. That forces Brett to chase a “job” that could permanently solve his financial situation.

Naturally, he loops Tony in. The younger man has his own money woes, which makes him willing to set aside his fears Brett is in over his head.

“Dragged Across Concrete” isn’t just about two troubled cops. The story also zooms in on Henry Jones (Tory Kittles, excellent), an ex-con trying to care for his mother and disabled brother.

Along the way we meet a new mom going back to work for the first time, a soulless killer clad from head to toe in black and Brett’s daughter and wife, a woman grappling with MS.

Zahler deposits them into the narrative in ways few filmmakers do. They interrupt the flow, leaving you scratching your head as to their purpose.

Let’s repeat: There’s always a method to Zahler’s madness.

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The film still can’t cover up some nagging flaws in his fascinating formula. Some anti PC dialogue sounds like monologuing more than real conversations. Raging against couples who say, “we’re pregnant” is a cute put down. It still feels calculated.

The screenplay offers plenty of great lines otherwise, conversations that deep dive into the characters’ hearts. This isn’t Tarantino-esque banter, baroque and self-referential. Zahler’s scripts have a cadence, a crackle, all their own.

It makes spending time with these characters a pleasure … to a point. No matter how engaging the banter proves, do we need to feel like we’re on an actual stakeout while watching characters on a stakeout?

“Concrete” dares you to identify with people who harbor some hate in their heart. Brett’s wife (Laurie Holden) says she’s as liberal as an ex-cop can be. She still seethes over the minority teens harassing her daughter.

Is she racist for drawing those conclusions? “Concrete” lets the viewer decide.

FAST FACT: S. Craig Zahler is more than a filmmaker. He co-wrote the music for “Dragged Across Concrete.” His work as a novelist includes the western noir “A Congregation of Jackals: Author’s Preferred Text” and the more recent “Hug Chickenpenny: The Panegyric of an Anomalous Child.”

Brett’s selfish nature, and unwillingness to own up to his mistakes, is far less forgivable. But he’s tired, oh, so tired. The actor captures that in his walk, his body crying out for rest while his mind races ahead.

“Dragged Across Concrete” is violent to the core. It’s how Zahler shapes that violence that’s so fascinating. It’s never without consequence, nor is it sugar coated in any fashion. One death in particular will make your heart ache thanks to a storytelling tangent you thought didn’t matter.

Boy, does it ever.

You could slice and dice 20 minutes from “Dragged Across Concrete” and leave the story unchanged.

Maybe more.

Would it still have that texture, that sense of impending doom that explodes in the third act? It’s hard to say. What’s clear is that we’ll sit through everything Zahler throws our way to see where he’s going next.

HiT or Miss: “Dragged Across Concrete” is maddening and mesmerizing in fitful doses, another violent tone poem from the most arresting voice in genre filmmaking.