("National Treasure: Book of Secrets," the but-of-course sequel to the 2004 Nicolas Cage blockbuster, is a letdown.

It contains all the elements from the original "National Treasure," which was a kind of "Da Vinci Code" on steroids crossed, rather charmingly, with American History Trivial Pursuit. But that's the problem: It's virtually the same movie with new locations. Oh, plus Helen Mirren. Not a bad addition, but the popcorn fun is gone.

Not that it will matter. Industry trackers insist those surefire box office elements will propel "Book of Secrets" to an even higher worldwide gross than the original's $347.5 million.

The film jets from one major historical monument of Western civilization to another with Cage's Benjamin Franklin Gates racing against time to solve an ancient puzzle for essentially no real reason. This yields well-photographed tourist sites, several cliff-hanging sequences -- a few literally that -- and a capable returning cast playing now-familiar roles in an action-fantasy.

Yes, action-fantasy is all you can call a film that abandons any semblance of reality. Take a major set piece: If you are going to stage a slam-bang chase sequence with cars smashing aside all objects, inanimate or human, guns blazing and no care for life or limb, the one city where this will not work is London: 9/11 cameras are everywhere on its tiny, pedestrian-choked streets and lanes, and security is the most stringent in Europe. Yet director Jon Turteltaub stages a sequence that tries to outdo "Bullitt," "The French Connection" and all the "Bourne" movies combined in the heart of London without a single bobby showing up. Right.

The story, more a blueprint for stunts than a coherent tale, was cobbled together by the husband-wife team of Marianne and Cormac Wibberley with the story credit divided among the Wibberleys, Gregory Poirier, Ted Elliott and Terry Rossio. The central notion, derived from the original "National Treasure," is that those dastardly Masons buried secret codes and puzzles -- treasure maps, as it were -- into major American documents, monuments and even furniture. Only Cage can penetrate their secrets.

This one centers on the assassination of President Lincoln by John Wilkes Booth. Wouldn't you know a Gates ancestor named Thomas was at the center of the action on April 14, 1865, and that the assassination was really about treasure maps and Mason secrets rather than the most heinous criminal act in American history.

Since a new piece of evidence brought forward by Ed Harris' rather suspicious Mitch Wilkinson appears to implicate poor Thomas Gates in the assassination, this is cause alone for Ben to spring into action. Which in turns ignites the burners of Jon Voight as Ben's eminent (though technologically challenged) professor-father Patrick; Mirren as his mom, who for plot convenience can translate ancient Indian texts; Diane Kruger as ex-girlfriend Abigail, who for plot convenience happens to be a history archivist; Justin Bartha's Riley, a techno-whiz who can break into any place, no problem; and Harvey Keitel as the FBI agent who cannot decide whether to arrest Ben or pin a medal on him.

The story requires Ben and company to jet to Paris to examine a Statue of Liberty replica in the Luxembourg Gardens, break into Buckingham Palace, then the White House Oval Office, kidnap the president (Bruce Greenwood), ransack the Library of Congress and finally discover an American Indian archeological site implausibly located under Mount Rushmore. Here much of the cast -- in a repeat of the earlier film's climax in catacombs beneath Manhattan -- hang from decaying ladders and dodge falling debris in an underground space the size of the Grand Canyon.

But the thrill is gone as everyone is slavishly following an action memo dictated by marketing concerns and boxoffice demographics rather than cinematic invention. No credible reason is ever given for the huge race. There is no ticking clock here other than Mitch and his goons being hot on Ben's trail, again for no logical reason. Family honor is one thing, but are you really going to destroy half of London and kidnap the American president over that?