Ron Howard has never directed a film this darkly surprising. And so the less said the better about the methods he uses to penetrate the schizophrenic mind of John Forbes Nash Jr. (Russell Crowe), the real-life Princeton mathematician who won a Nobel Prize in 1994. Crowe, an Oscar winner last year for Gladiator, rises to the challenge of the role with fearless integrity. He’s electrifying. Points too for Jennifer Connelly, luminous and touching as Nash’s long-suffering wife; Paul Bettany as his Princeton roommate; and Ed Harris as a CIA operative. Screenwriter Akiva Goldsman, juggling the facts in search of a more elusive truth, maps a harrowing journey for the audience. Sadly, Howard blands out in the final third, using old-age makeup and tear-jerking to turn a tough true story into something easily digestible. Until then, you’ll be riveted.