Recent chapters in the cultural history of nerds have focused on how these magical creatures end up making far more money than the rest of us. Heralded by the hyperventilations of Wired, the digital wunderkinder of the 1990s Internet boom were praised and blessed with conjured millions. “21,” which opens Friday, is based on other brainy beneficiaries of easy money from that decade who skirted the line between con and cognition, but its formulaic plot adds little to the weekend must-see list, much less the grand nerd narrative.

The escapade, thanks to Ben Mezrich’s 2002 best seller “Bringing Down the House,” is already well-known: In the early ’90s, a ring of card-counting MIT students turned Vegas blackjack into a reliably profitable science. Reset to the present, “21” relates the titillating highs of floppy-haired newbie Ben Campbell (Jim Sturgess) after he joins a blackjack squad that beats the casinos, and the lows that result from crossing Kevin Spacey.

Young Ben is happily enrolled at MIT with two robot-building friends and a part-time job selling prep-wear when a professor, Micky Rosa (Mr. Spacey), notices his prodigious math skills. Apparently unsatisfied with tenure, Micky also runs a team of card-counters as a business, and recruits Ben, who needs to bank cash for medical school (here a whiff of “Good Will Hunting” creeps in). Micky and the students school the new guy in their technique: A spotter at a given table watches until a depleted deck gets hot with face cards, then signals a teammate to clean up with big bets. (Arithmophobes can relax: The movie displaces the book’s explanatory energies from probability to the catchy codewords used by the spotters.)

Our heroes are off to Vegas, laden like drug mules with thousands of dollars in betting cash, and the usual nips and tucks are made to the original true story. Ben is joined by an arresting blond love interest and voice of reason (Kate Bosworth). Cole, the casino’s eye-in-the-sky (a bored Laurence Fishburne), has added basement beatings to his repertoire of surveillance cameras. And Ben himself, as Internet devotees shriek, is no longer Asian — as in the book and real life — but white.

The sight of whiz kids under the glitz of Vegas, robbing it blind, packs far too mush wish fulfillment and Schadenfreude to be a total bust. But the driving-school turns of the plot suggest that magazine-feature premises attract lazy screenwriters (here, that would be Peter Steinfeld and Allan Loeb). Micky gets too angry too quickly when Ben loses focus, and the lad’s downfall at his mentor’s influential hands has that prole-baiting “Enemy of the State” rapidity that burns bridges with credibility.

Also, and maybe most important, Vegas should just look like a lot more fun for a college kid racking up thousands per night. As if tacking democratically away from “Ocean’s 11” glam, “21” eschews the marquee fight nights, quick changes, and celebrity sightings of the original book, and reduces Ben to enjoying the run-of-the-mill excitement of strip-club peekaboo and — hold on to your hats — late-night room service. Maybe it’s no surprise that Mr. Sturgess’s voice-over sounds dejected at times; Hollywood should bring the excess.

But Ben is a somewhat humbler figure than the book’s star, and Ms. Bosworth’s character, essentially a shy-guy trophy, is admittedly nothing to sneeze at. Still, a double life has to be more exciting than this, and Mr. Sturgess isn’t the most gripping of young actors (though he is a relief compared to the hardened mask of smugness presented by the ever-enunciating Mr. Spacey).

The green-felt, born-loser romanticism of classic gambling flicks has little to do with this movie, but “21” (from the director of “Legally Blonde” and “Monster-in-Law”) trades its own potential for nerd cool for a limp final chase and a musty moral. As a former member of the actual MIT crew recently said of her card-counting past, “It’s totally legal to use your brain.” The filmmakers act as if they’re not so sure.