Blackjack aficionados have already thrilled to Ben Mezrich's book Bringing Down the House, a true story about a group of MIT students/blackjack card counters who shake down Vegas for millions of dollars. In a nutshell: A professor organizes a team of math whizzes who have a gift for remembering numbers ("card counting" is just that—recalling what cards have been dealt, and taking advantage when a deck gets hot). The team flies to Vegas every weekend, uses a complicated system of visual and verbal cues, and transforms themselves into sexy, big-spending "whales." After making a crap-ton of cash, they hop back on the plane, return to their classes, and live as anonymous math nerds.

It's an enjoyable book with an undercurrent of danger roiling underneath: Card counting isn't illegal, per se, but if counters are caught, a visit to the spurned casino's basement is reportedly a very unpleasant one.

Director Robert Luketic (Legally Blonde) takes this inherently interesting tale and crams it through the Hollywood Script-o-Matic 2000™ to bring us 21—starring the hottest math nerds you're ever likely to meet (including Kate Bosworth). To his credit, Luketic makes full use of Vegas' photogenic nature, and the cinematography is gorgeous in its allure. Additionally, the story itself is fascinating enough to carry one happily to the third act. Unfortunately, the script and acting is so by the numbers, it's hard to root for anyone involved—including the usually reliable Kevin Spacey (who's quickly becoming the Al Pacino of phoning in performances).

Worst of all, the filmmakers scrap the end of the book to deliver a rote "cross, double-cross, quadruple-cross" ending that's entirely superfluous and eye-rollingly stupid, making 21 another great example of why we'd rather watch something good on TV than pay to see something mediocre at the theater. In other words: Color up and cash out.