Have you ever heard the phrase “The house always wins” when talking about gambling against a casino? Well when it comes to “21,” a flashy adaptation of Ben Mezrich’s compelling New York Times bestseller, the book always wins.

You can start with Mezrich’s superior title, “Bringing Down the House,” which unfortunately belongs to a regrettable Steve Martin-Queen Latifah comedy. Changes, not always for the better, continue from there.

Both the book and the movie recount how a team of math whizzes from the Massachusetts Institute of Technology made millions counting cards at Las Vegas blackjack tables. Mezrich was handed the story by team member “Kevin Lewis” – a bogus moniker used by team member Jeff Ma. Under the guidance of former card counter Mickey Rosa, the MIT geniuses milked Vegas, Atlantic City and a slew of riverboat casinos east and west of the Mississippi River until sophisticated facial-recognition software made it impossible for them to complete their elaborate scams.

“House” raises a number of interesting arguments, most of which “21” ignores. The book explains how Rosa insisted on recruiting mostly Asian and Persian numbers gurus because inherently racist casino owners would dismiss them as heirs to the Sony Corporation or children of wealthy sheiks who were content to gamble away daddy’s fortune. White kids, however, who were blowing money at the card tables would raise red flags.

So who does “21” director Robert Luketic cast as his MIT card counters? Marketable lily-white bombshell Kate Bosworth, British charmer Jim Sturgess (“Across the Universe”) and American actor Jacob Pitts. All three are decent actors, though they wouldn’t last 10 minutes in the bowels of the famed Bellagio resort and casino. Aaron Yoo and Liza Lapira are the lone Asian actors in the ensemble. They have precious few lines.

Mezrich goes on to explain that card counters have little to fear in Vegas today because major corporations own the top casinos, and they’d never risk the possibility of a lawsuit by strong-arming a patron in a clichéd back-room encounter. But that’s not dramatic, and so “21” hires Laurence Fishburne as a security chief eager to make a bust because the facial-recognition software is making him irrelevant. The actor is adequately menacing, though the nugget-sized rings on his clenched fingers steal his thunder.

Calling a book better than its movie is hardly earth shattering, and “21” doesn’t completely bust. It just softens its stance as screenwriters Peter Steinfeld and Allan Loeb attach a number of generic Hollywood elements to Mezrich’s unique story. Even the Mickey Rosa character, so hideous in the book, almost reaches mentor status before Kevin Spacey infuses him with the proper sleaze. Seeing Spacey freeze out his cohorts doesn’t permit the Scooby Doo footrace that concludes “21,” but those going all-in on the premise won’t care too much.

“21” is a stylish upgrade for Luketic, who previously helmed light romantic comedies like “Legally Blonde” and “Win a Date with Tad Hamilton.” Overlooking the overwrought Vegas mystique, Luketic opts for the sexy gloss of Sin City and finds a party vibe that will appeal to younger crowds. It’s flashy, if a little flat.

I’m not ready to declare that movies set in Vegas should stay in Vegas. (I’ll reserve that judgment for the upcoming Ashton Kutcher-Cameron Diaz comedy.) But thanks to drastic “improvements,” the “21” adapt-ation is about as dangerous as betting the minimum at the $5 tables.