The heist doesn’t go wrong. Five guys, some dressed as clowns, one wearing a priest’s collar and the getaway guy in a fire chief’s uniform – knock over the cash office of the Ohio State Fair.

But just afterward, four of the robbers – Michael Chiklis, Wendell Pierce and Clifton Collins among them — turn on the calm and collected fifth guy. They shoot him and dump him on the backroads of Kentucky.

And to “Parker,” that just won’t do.

“Civilized people need to follow the rules,” Parker (Jason Statham) insists. It’s not just his share of the loot that they took, “It’s the principle.”

So he proceeds to drag his bloody, patched-up body of the hospital to ruthlessly pursue these mob-connected bad men to New Orleans and then West Palm Beach, pursued by a knife-wielding hitman who may get to him or his laying-low girl (Emma Booth) first.

And West Palm is where the broke and comically lonely realtor (Jennifer Lopez) figures into the plot.

Veteran director Taylor Hackford (“An Officer and a Gentleman”) does well in creating this underworld, where there truly is no honor among thieves, where Parker’s girlfriend is the daughter of a thief (Nick Nolte) and never questions what he does or may suffer in his line of work – even in the flashback shower scenes where she fondles his many scars.

Hackford, in his heyday, was famed for framing attractive women in body-part close-ups.

He and his screenwriter get the idea that a knife fight – there are a few – is much scarier than a simple, “neat” shooting. It’s how hard men with nothing to lose might tangle, even if there are trunkloads of guns available.

But “Parker” has devolved from the Donald Westlake novel about a vengeful robber – named “Walker” in 1967’s “Point Blank,” and “Porter” when Mel Gibson played him in “Payback”in 1999  – into an equally violent cut-and-paste Jason Statham vehicle. The guy’s heartless streak – he kneecaps bank guards without a thought and strangles a hospital nurse to escape – has to be softened by a “nobody gets hurt who doesn’t deserve to” ethos.

Hackford makes this Parker talk WAY too much. Statham, notorious for choosing films based on the fight choreographer he gets to work with, brings the brawn. But he’s not as good in conversations. The movie’s already talked-out and dragging when we finally get to J. Lo.

And J. Lo stops the picture cold. Not with her performance so much. But the character is overwritten, big speeches. She won’t shut up. Parker makes her strip — an obligatory and gratuitous “Girlfriend’s well preserved” moment.

She’s got a shrill mama (Patti Lupone) who takes to Parker at his bloodiest – no questions asked.

Despite an epic fight or two, “Parker” robs us of the revenge, the suspense of the hunt, of Parker’s methodical way of tracking down those who betrayed him, one by one. It’s one thing to not literally repeat previous films of an oft-filmed tale. It’s another to make all these changes to the formula and not find one single surprise to shove in it.

(Is this the worst movie going weekend of 2013?)

MPAA Rating: R for strong violence, language throughout and brief sexual content/nudity

Cast: Jason Statham, Jennifer Lopez, Michael Chiklis, Patti Lupone, Clifton Collins, Wendell Pierce, Bobby Cannavale

Credits: Directed by Taylor Hackford, written by John J. McGlaughlin, based on the Donald Westlake novel . A FilmDistrict release.

Running time: 1:58