It’s a filthy place, this “Broken City.” Even the people called “good guys” have their dark side, their dirty secrets and tragic flaws.

And the “bad guys?” They’re all over the New York papers, all over New York cable news - a mayor who plays hardball, a guy running against him who’s not above crawling in the mud, a police commissioner too quick to make ethical compromises.

“Broken City” begins with a cop, ably played by Mark Wahlberg, on trial for a shooting that may not be as cut-and-dried as he maintains. The mayor (Russell Crowe) slaps him on the back, and says “I like having my picture taken with heroes.” But he and the police chief (Jeffrey Wright) end Billy Taggart’s career, no matter what the judge says.

Cut to seven years later. Billy’s a private detective - skulking in alleys, photographing cheating spouses. He’s got a hot actress wife (Natalie Martinez), and his work has made him the jealous type. He’s got a lot of bills and a bad temper.

At least he’s on the wagon.

That’s the moment his old pal, the mayor, calls. Find out who’s sleeping with my wife, Hizzonor says. Do it before Election Day, next week. The can-do mayor is in a two-fisted race with a city councilman (Barry Pepper). The last thing he needs is for word to get out that his wife (Catherine Zeta-Jones) is cuckolding him.

But once Billy has done his job and gotten the incriminating photos things turn even dicier. The adulterer turns up dead and Billy wonders if he’s been set up. His life unravels even as he and his perky assistant (Alona Tal) unravel the layers of deceit surrounding this case.

Director Allen Hughes (“The Book of Eli”) hides the secrets well and stages a good fight and chase. But what’s most entertaining about Brian Tucker’s script is the lived-in feel it has. The ex-cop is all rough edges, intolerant at times, ill-tempered. And funny.

His assistant calls something “wondrous.”

“Wondrous?! Did they teach you that at DeVry?”

Politicians treat slander with the cavalier disregard of those used to an “any means necessary” style of campaigning. “It won’t stick. But it’ll smudge.”

Working-class cops and politicians have homophobic streaks. Wright’s police chief-turned-police commissioner has a simmering resentment that feels righteous, but unsavory. Crowe plays the mayor’s working-class background as a barely hidden resentment, making him menacing even when he’s glad-handing supporters.

Jones has a decent part to play as well, a woman challenging the private eye on what he thinks he knows.

There’s a lot of background to pack into every character, and Tucker sets them up as virtuous, pure of motive, only to pull the rug from under them.

But “Broken City” doesn’t have a compelling narrative to pull it along. Wahlberg, playing well within his comfort zone, dials back the fearsome, aiming for funny some of the time. It’s a hallmark of this slightly-better-than-average thriller that it is missing some of the requisite thrills. And that Wahlberg blows his best one-liner.

This mayor is “dangerous,” he’s warned. Naah, Billy flatly replies.”He only knows people that kill people.” Emphasize the “KNOWS” and that line sings.