Directed by Jon Turteltaub, National Treasure is as complicated as a calculus formula. Ben Gates (Nicolas Cage) is an nth-generation crackpot. A long series of Gateses have believed they've been let in on the biggest secret in the history of buried treasure. Their story holds that the last living signer of the Declaration of Independence told Ben's nth great-grandfather that George Washington, Benjamin Franklin and a lot of other Founding Fathers who held membership in the society of Free Masons had buried an immense treasure during the Revolutionary War to make sure it didn't fall into the hands of the British. Nth great-gramps was also outfitted with some clues as to where the treasure was buried. Since then, one Gates after another has pursued the clues from frustration to humiliation. Ben's granddad (Christopher Plummer) still believes in the treasure and the clues. But Ben's dad (Jon Voight), who was a believer in his youth, is now an embittered apostate who thinks the clues are a cruel hoax. So it's up to Ben to carry on the tradition of family folly.
The movie alleges that the treasure was looted from the Holy Land (that is, the Muslims) during the Crusades by the Knights Templar. Subsequently, the treasure was transported from Asia to Europe to America, though this seems odd since Europeans didn't get into the future United States until the 16th century and the last of the Knights Templar was burned at the stake in 1314. I guess this is where the Masons come in. Anyway, the treasure arrives in the New World because the Knights Templar didn't want it to fall into the hands of any king because a king would no doubt use it for bad things. England had a king, so George Washington and his fellow Masons didn't want England to have it. Hence they buried it, made up a bunch of clues about its whereabouts that they placed on our currency (check out a dollar bill and ask yourself what's with that pyramid and that spooky eye), scribbled on the back of the Declaration of Independence in invisible ink and confided to Ben's nth great-grandfather.
Or at least Ben believes that's what happened and has managed to convince millionaire Ian Howe (Sean Bean) to back various adventures provoked by the clues, one of which leads Ben and Ian to the North Pole to discover the wreck of an ancient freighter that is nicely located directly under the first place in a vast frozen tundra where Ben decides to chop at the ground with his ice axe. The treasure isn't actually on the ship, and that's a good thing because the movie has just started, but there are some interesting clues on the ship that the treasure might be somewhere else, and that's a good thing because now Ben has some stuff to do for the rest of the movie. The trip to the North Pole is also good because it so frustrates Ian that he decides to kill Ben, and that provides the movie with a badly needed villain.
Eventually, the clues on the ship point to the Declaration of Independence which Ian determines to steal and Ben determines to steal first so that Ian can't desecrate one of our sacred national treasures (get it!). This leads to the wooing of national archivist Abigail Chase (Diane Kruger) who seems inadequately devoted to national archivism, the indignation of the FBI and its agent in charge (Harvey Keitel), and the requisite scenes of flight and pursuit, capture and escape. What would an action movie be without them? None of this is remotely believable, of course, but when did that matter? It's breathless and cleverly enough convoluted that you do shake your head in a laughing concession of wonder. But the movie doesn't send you, and that's because Cage doesn't dare to take Ben to the lunatic fringe where his character ought to reside, whether the treasure is real or not. And about this last I'm staying mum, though I will say that if the treasure is where Ben thinks it is, there's no way the Masons could have kept it a secret from the British. But what's logic got to do with an action movie?