Nicolas Cage and his rapidly receding hairline return in the form of the world's oldest, most enthusiastic Eagle Scout in the enjoyably preposterous adventure sequel National Treasure: Book Of Secrets, a film that plays like The Da Vinci Code as re-imagined by well-meaning but clueless high-school history teachers. Like its predecessor, it's patriotic pornography, with earnest speeches about our country's distinguished history serving as the money shots. It must have taken tremendous force of will not to simply subtitle the film U.S.A.! U.S.A.! U.S.A.!.

Comfortably embracing self-parody, Cage plays a wide-eyed do-gooder who springs into action when his great-great-grandfather is slandered as a conspirator in a plot to kill Abraham Lincoln. Teaming up with dad Jon Voight, ex-girlfriend Diane Kruger, and incongruously non-geeky geeky sidekick Justin Bartha (the only computer nerd in film history who could moonlight as an underwear model), Cage follows a trail of clues that lead him to Buckingham Palace, then the White House, and finally to Mount Vernon, where he must kidnap the President (Bruce Greenwood) in order to find a book of Presidential secrets and a lost city of gold. Then things start to get a little silly.

It's a measure of the film's infectious goofiness that Cage seems altogether more interested in clearing the name of a long-dead ancestor than in finding a city of gold. The film affords him some excellent opportunities to unleash his inner ham, particularly during an epic freak-out at Buckingham Palace and an animated argument about Lincoln's death with a small boy at a White House Easter-egg hunt. Screenwriters Cormac and Marianne Wibberley seem to be challenging themselves to cram as many hilariously convoluted, over-the-top twists into the film as they possibly can; it must be awfully liberating never having to worry about plausibility or realism. Still, given its two-hour-plus running time, Secrets could easily lose 20 minutes, especially once it runs out of energy toward the end. But it's fun, goofy, and fleet enough to merit a third go-round. Heck, maybe in the next adventure, Cage could uncover a conspiracy involving a bunch of pagan bitches and their evil plot to reap a rich honey harvest. That premise is a proven laugh-getter, albeit of the unintentional variety.