Ben Franklin Gates (Nicolas Cage) is an honorable treasure hunter, sharing a penchant for preserving, and not stealing, artifacts with a beloved whip-cracking hero from the 1980s. Too bad the National Treasure movies he shows up in don’t quite have the same mythological zeal.

Vastly more complicated than the original, Book of Secrets ups the dramatic ante with greater conviction, trots the globe with more spring in its step and welcomingly adds co-stars Ed Harris and Helen Mirren, who could’ve classed up Norbit. Returning director Jon Turteltaub also has great fun with the rare climactic standoff that involves weight distribution. Oh yeah, and it innovatively uses Abraham Lincoln’s assassination as its springboard to 218 years of conspiratorial revelations.

Yet like its predecessor, Book of Secrets is so wired for a whiplash of historical clues and so breathless to send us above, inside or below the next national landmark, that there’s too much magic missing. There are fleeting moments, but not enough, and Trevor Rabin’s pushy score — which could make even flossing seem like the life-or-death act your dentist says it is — is no help.

On April 15, 1865, Ben’s great-grandfather, Thomas (Joel Gretsch), is asked to decode a cipher in a diary belonging to John Wilkes Booth. Upon learning of Lincoln’s death, Thomas torches the cipher and pays for it with his life. After it’s revealed the cipher would’ve led the Confederacy to stock its war chests with ancient treasure, Thomas is celebrated as a modern-day hero.

That is, until Mitch Wilkinson (Harris) — goofily described by Cormac and Marianne Wibberley’s script as a mercenary/black-market antique dealer — turns up with a page from Booth’s diary suggesting Thomas headed the conspiracy. Eager to find the treasure and clear Thomas’s name, Ben and father Patrick (Jon Voight) decode the cipher, captured as an impression on Mitch’s page.

Sidekick Riley (Justin Bartha), enmeshed in tax debt and unsuccessful as a writer, and girlfriend Abigail (Diane Kruger), from whom Ben is recently separated, also are back for the ride. And, along the way, their quest picks up Ben’s estranged mother Emily (Mirren), who mixes it up with Patrick.

They’re led to clues in Paris, London, Virginia and, ultimately, South Dakota that are connected to the Book of Secrets, an explanation of every national conspiracy theory that’s meant for presidential eyes only. JFK and Area 51 are mentioned in passing, but they’d be more interesting than a story in which the most intriguing discoveries come when someone crawls under a desk.

Cage has never looked waxier or performed with as much annoying “unpredictability,” namely during an embarrassingly long, loud and obnoxious distraction at Buckingham Palace. The film teems with so much product placement that the Gates family seems to have sought sponsorship. And little pieces of your brain might disintegrate each time the untalented Kruger speaks.

So aside from a cast that can say lines like “You can’t even get back to the long, round stone door!” without busting up, Book of Secrets generates what fun there is in much the same way as the original. Turteltaub stages another crackerjack car chase that requires quick thinking from Ben. The comic reliefs of Bartha’s geek chorus and Voight’s fussbudget father are diminished but still have some smiles. Plus, it’s a fitter, trimmer sequel, coming in at about two hours.

It’s just that the National Treasure films get too caught up in their own furious flurry to do enough for our Indiana jones.