The only muscles they never exercised were their brains.

OK, fine. The brain’s technically an organ. But it’s not like the members of the Sun Gym Gang would know the difference.

The trio of lunkheads at the heart of the midnight-in-a-coal-mine dark comedy "Pain & Gain" come off like the Three Stooges on steroids.

Convicted swindler Daniel Lugo (Mark Wahlberg) benches 400 pounds, squats 500 and shows up at a business meeting sporting a briefcase and jean shorts.

Paul Doyle (Dwayne Johnson), a hair-trigger violent, born-again recovering addict, is freshly sprung from Attica for a coked-up Christmastime burglary.

And Adrian Doorbal (Anthony Mackie), Lugo’s fellow personal trainer who’s suffering from "defeated phallus syndrome," will do anything for bigger muscles, including guzzling breast milk.

For his first self-described "little movie," director Michael Bay seems to be aiming for a comic caper that the Coen brothers and Carl Hiassen might have hatched in the supplements aisle of a GNC.

And surprisingly, given his "Transformers"-heavy resume, Bay comes dangerously close to succeeding.

Wahlberg’s Lugo is a dreamer — a thick-necked, even-thicker-skulled dreamer, but a dreamer nonetheless.

He idolizes Rocky, Scarface and the guys from "The Godfather" because they were self-made men. And he’s particularly susceptible to a get-rich-now seminar hosted by infomercial king Johnny Wu (a perfectly cast Ken Jeong).

So when Victor Kershaw (Tony Shalhoub), one of his smarmier Sun Gym clients, won’t stop flaunting his wealth — after all, he owns the Schlotzsky’s by the airport — Lugo decides that the fastest way to achieve the American dream is to steal it.

He enlists Doyle and Doorbal for what should be a simple snatch-and-grab, thinking they can kidnap Kershaw, have him sign over his fortune and then set him free without him ever learning their identities.

After a couple of failed attempts involving ridiculous costumes, hand signals and tactics gleaned from action movies, and less-than-superior logic — Lugo tells his cohorts the Delta Force could conduct the raid they’re planning in 53 seconds, but with the trio’s superior athleticism, it should only take them 40 — they get their man.

They just have no idea what to do with him once they have him.

Wahlberg, who packed on so much muscle for the role that he looks like a special effect, makes for an enjoyably dim ringleader — the kind who takes time to "get a pump" in the middle of cleaning up a crime scene.

But as both the team’s strongest member and its weakest link, Johnson is a revelation.

Wearing a succession of religious-themed T-shirts stretched across his massive chest, Johnson sinks his teeth into his best, most-layered role yet.

When Kershaw becomes convinced he’s not going to make it out alive, he lashes out at Johnson’s Doyle by declaring, "When I get to heaven, I’m gonna tell Jesus what you did." Doyle’s frightened response —

"You’re not gonna tell Jesus anything!" — is delivered with such childlike conviction, it’s hard not to root for the big galoot.

If this were "Of Mice and Muscleheads," Johnson would be playing Lennie Small.

But just when you think "Pain & Gain" couldn’t possibly get any darker than having a victim held hostage for weeks and beaten with sex toys (don’t ask), it does.

Exponentially so.

As over-the-top as things ultimately get — seeing Lugo and Doorbal return a chain saw clogged with human hair to Home Depot isn’t even the apex of its wrongness — "Pain & Gain" is based on a true story.

Screenwriters Christopher Markus and Stephen McFeely (the "Captain America" movies) adapted Pete Collins’ Miami New Times articles, and Bay goes to great lengths to remind you that what you’re seeing really happened. He even interrupts a particularly outrageous scene with the onscreen title, "This is still a true story."

It’s that kind of movie.

And it doesn’t always work.

For one thing, there are so many voiceovers and inner monologues that much of "Pain & Gain" could double as a radio play.

But there’s enough that does — especially Johnson’s character work, a low-key turn by Ed Harris as a private investigator and some laughs from Rebel Wilson as Doorbal’s penis nurse — to hold out hope that Bay can continue down this more-ambitious, less-commercial (at least for him) path.

Just as soon as he and Wahlberg finish shooting "Transformers 4."

Christopher Lawrence is the movie reviewer for the Las Vegas Review-Journal. Contact him at