The actor, teaming up with Annette Bening, does a sly job of playing a retired Midwestern dweeb, but this feel-good get-rich fable, while most of it actually happened, still feels tidy and thin.

Bryan Cranston has played his share of fuddy-duddy straight arrows, and when you see him in “Jerry & Marge Go Large,” you may just think, “Oh, he’s doing it again.” But Cranston is too fine an actor to merely phone in another nerd. As Jerry Selbee, a cereal-factory middle manager in Evart, Michigan, who’s getting ready to begin his (forced) retirement, Cranston wears big wire-frame glasses, the kind of short-sleeve plaid shirts that come in shades of lavatory yellow-green, and a bristly conservative haircut that lends him a droid-like reserve. The character is every bit as wholesome, square, and aw-shucks genial as he looks. Cranston makes him a dry-voiced dweeb without edges or demons; he might be George H.W. Bush’s mild-mannered Midwestern cousin. Then again, we know there’s got to be some dimension to the guy or Bryan Cranston wouldn’t be playing him.

Jerry has spent 42 years working at the local Kellogg’s plant and has been married to Marge (Annette Bening) since they were 17-year-old high-school sweethearts. Marge is tart in a cuddly way; they’re two frumpy peas in a pod (even if they haven’t had sex since they can remember). Jerry is the kind of man you might call boring, except for one thing: He’s a wizard at math. It’s more than a skill; it’s his defining trait — the way he sees the world, breaking down everything into systems. He’s a little like a savant, except that he’s not autistic. He’s just a bit remote, stuck in his numbers head.

During the early weeks of his retirement, when he has no idea of what to do with himself (he’s only 62), Jerry is in the local coffee shop and happens to glance at the back of a brochure that’s sitting on the table; it’s the fine-print rules for the local lottery, the WinFall. Within seconds, his numbers-crunching mind has spotted something: There’s a loophole — a soft spot — in the lottery’s system. The odds, as in any gambling situation, have been designed to favor the house — which, in this case, would be the state of Michigan. That’s how it’s meant to work. But the WinFall lottery has a “roll-down,” which means that when the jackpot reaches a certain number (in this case, $5 million), instead of going up from there the money rolls down to smaller bets, which are easier to win. And what Jerry has noticed is that the statistical odds of winning, if you buy enough roll-down tickets, actually favor the lottery player.

In other words, if Jerry buys enough tickets, he can’t lose.

He goes into the bank, withdraws $2,000 from his checking account, and buys that many tickets. He winds up with a loss. But he immediately figures out why. His sample simply wasn’t big enough. As Jerry explains to his clueless accountant (Larry Wilmore), it’s like flipping a coin: If you do it only a certain number of times, you may not get a 50-50 heads/tails split — but if you do it 10,000 times, the probability increases that you’ll get almost exactly 50-50. The math approaches a perfect mean the more times you do it. So Jerry goes back to the bank and withdraws $8,000, which is all that’s left in the account. He buys that many lottery tickets, and sure enough, he winds up winning nearly $16,000. He then invests all of that in more tickets, and the same thing happens. He has found the perfect betting system, with no luck involved.

“Jerry & Marge Go Large” opens with a title that reads “Inspired by a true story. In all probability.” That’s all very cute and might make you think, Oh, so this isn’t quite a true story? In fact, the film stays very close to the actual saga of Jerry and Marge Selbee, a pair of Michigan homebodies who sustained their secret and totally legal lottery scheme for years, winning a total of $26 million. (They wound up on “60 Minutes.”) They didn’t hoard it all either. They formed a corporation so that members of the local community could take shares in the betting, which would net each participant a profit — and guarantee the total winnings all the more. “Jerry & Marge Go Large” tells this story in a quaintly homespun, feel-good way that nods to Old Hollywood comedies like “You Can’t Take It With You” and “The Miracle of Morgan’s Creek” and also to ’90s small-town-scheme indie crowd-pleasers like “The Full Monty” and “The Englishman Who Went Up a Hill But Came Down a Mountain.”

The movie is a fable of winning, of beating the house every time, without much of a dark side. In that way, it’s fun; it allows us to coast along on our vicarious desire to get rich by beating the system, the way people who trade penny stocks based on “hot” tips do. “Jerry & Marge Go Large” is an agreeable lark, yet there’s something a bit prefab about it. The director, David Frankel, is a commercial filmmaker who, at his best, has shown some real personality. He made the very good Sarah Jessica Parker movie “Miami Rhapsody” (1995), followed by “The Devil Wears Prada” (2006) and “Marley & Me” (2008), which I think is one of the best canine movies ever made, and also the wised-up marital comedy “Hope Springs” (2012). “Jerry & Marge Go Large” is likable, but compared to those previous Frankel movies it’s also tidy and thin. It’s like the pilot for a quirky small-town TV series — a “Northern Exposure” of revenue enhancement — and it’s goosed along by one of those intrusively upbeat musical scores that keeps telling us, “You’re having a wacky good time! At the movies!”

When the WinFall lottery gets closed down in Michigan, Jerry and Marge realize that they can continue their scheme in Massachusetts, where the lottery is up and running. So they develop a ritual: As the roll-down happens, about every three weeks, they hop in their pickup truck and take the 10-hour drive to Massachusetts, rent a room in a charmingly grungy out-of-the-way motel, and buy their thousands upon thousands of lottery tickets at the Liquor Hut, a roadside convenience store owned and operated by Bill (Rainn Wilson, in a bushy orange hipster beard), who becomes their partner in (non) crime. It takes several days for the machine to print out all the tickets they need — and many days, in the motel room, for Jerry and Marge to go through the multiple crates’ worth of tickets to find the winners. But because they know they’re making hundreds of thousands of dollars each time, they love the process. It becomes exciting to them — and, in an inevitable scene, re-sparks their love life.

So where’s the conflict? A Boston Globe reporter starts to sniff around the lottery, ultimately figuring out that the winners are coming from one area — and, in fact, the Selbees really were outed by a Globe reporter. The other conflict is one invented strictly for the film, in the form of a treacherous rich kid from Harvard, Tyler Langford (Uly Schlesinger), who figures out the same loophole Jerry did and starts to play the lottery the same way. You’d think there’d be enough money to go around, but Tyler, a budding yuppie sociopath, wants all the profits for himself. This is the worst part of the movie, because you never totally buy this baby-faced cliché villain. You just realize the film needs something to spank it along.

Most of the events in “Jerry & Marge” really happened, but the movie still plays like a Wiffle-ball fantasy for our own economically stressed-out times. If only every state gaming craze had a loophole! And we were mathematically inclined enough to spot it! Jerry, the rustic Middle American math wizard, is like James Stewart with a pocket protector, only he’s protecting the whole community. (A number of Evart residents who signed on with him used the money to put their kids through school.) Yet maybe one reason that the tale, as appealing as it, doesn’t have much resonance is that the whole meaning of it ends up being just a quirk. Jerry Selbee figured out a way to beat the system. The truth is that the system has figured out a way to beat just about everyone else.

A Variety and iHeartRadio Podcast