Less engrossing than its 2004 predecessor National Treasure, Jon Turteltaub's busy sequel National Treasure 2: Book of Secrets is nevertheless a colourful and witty adventure, another race against overwhelming odds for the answer to a historical riddle. Ben Gates (Nicolas Cage), the treasure hunter who feverishly sought, in the first film, the whereabouts of a war chest hidden by America's forefathers, is now charged with protecting family honour. When a rival (Ed Harris) offers alleged proof that Gates' ancestor, Thomas Gates, was not a Civil War-era hero but a participant in the assassination of Abraham Lincoln, Ben and his father (Jon Voight) and crew (Justin Bartha, Diane Kruger) hopscotch through Paris, London, Washington DC, and South Dakota to gather evidence refuting the claim. The film is most fun when the hunt, as in National Treasure, squeezes Ben into such impossible situations as examining twin desks in the queen's chambers in Buckingham Palace and the White House's Oval Office, or kidnapping an American president (Bruce Greenwood) for a few minutes of frank talk. Helen Mirren, the previous year's Oscar winner for Best Actress, wisely joins the cast of a likely hit film as Ben's archaeologist mother, long-estranged from Voight's character but as feisty as the rest of the family. Returning director Turteltaub takes excellent advantage of his colorful backdrops in European capitals and the always-eerie Mount Rushmore, and oversees some wildly imaginative sets for this dramedy's feverish third act in an audacious and completely unexpected, legendary setting. If National Treasure 2: Book of Secrets doesn't feel quite as crisp and unique as its predecessor, it is still ingenious and wry enough to laugh a bit at itself. --Tom Keogh