An unconvincing exercise in moral complexity; 21 is based on Ben Mezrich's book Bringing Down the House: The Inside Story of Six M.I.T. Students Who Took Vegas for Millions. Jim Sturgess (Across the Universe) plays brilliant; blue-collar scholar Ben Campbell; whose doubts that he'll win a scholarship to Harvard Medical School compel him to join a secret; M.I.T. gang of math whiz kids. Under the silky but chilling command of a math professor (Kevin Spacey); Jim and the others master card counting; i.e.; the statistical analysis of cards dealt in blackjack games. The team lives a humdrum existence during the week; but on weekends in Sin City; the students are rolling in cash; going to exclusive clubs; and feeling on top of the world. (Ben even gets the girl: a comely; fellow counter played by Kate Bosworth.) Despite all that success; Ben feels ethically compromised; and indeed director Robert Luketic (Legally Blonde); in the old tradition of American movies; plays it both ways where fun vices are concerned. On the one hand; it feels so good; on the other; ahem; we know it's wrong. That studied ambivalence proves wearing after a while; making the most interesting character in the film a casino watchdog played by Laurence Fishburne. A master at reading the emotions of gamblers beating the house with a scam; he's admirable for being good at his job; but repellent for wrecking the faces of counters in casino dungeons. He's all about moral complexity in the tradition of anti-heroes; and a truly provocative element in an otherwise superficial movie. --Tom Keogh