He travels to Paris, France, where he finds a clue engraved on the torch of the smaller model of the Statue of Liberty. Refusing to allow his ancestor's name to be tarnished, Ben discovers a cipher pointing to Édouard Laboulaye hidden on the back of the diary page. Black market dealer Mitch Wilkinson (Ed Harris), a Virginia Military Institute graduate, shows one of the 18 missing pages of John Wilkes Booth's diary, with Thomas Gates' name on it, convincing everyone that Thomas was not only a conspirator, but the grand architect of the Lincoln assassination, which tarnishes the Gates family's reputation and Ben is disgraced. As Thomas dies, Thomas tells his distraught son, Charles Gates, 'The debt that all men pay.' Over 140 years later, Ben Gates (Nicolas Cage) is telling his great-great-grandfather's story at a Civilian Heroes conference. Thomas is shot, and the gunman attempts to retrieve the pages, but only obtains a page fragment. A fight breaks out, and Thomas rips several pages from the diary and throws them in the fireplace. Thomas solves the puzzle, a clue to a map to Cibola, the city of gold, and realizes the men are still loyal to the South and have a sinister motive for finding the treasure. While he does so, Booth leaves for Ford's Theatre to assassinate President Abraham Lincoln.

Thomas recognizes the message and begins to translate it. Five days after the end of the Civil War, John Wilkes Booth and Michael O'Laughlen, both members of the Knights of the Golden Circle (KGC), enter a tavern and approach Thomas Gates (Ben Gates' great-great-grandfather), a well-known puzzle solver, to decode a message written in Booth's diary. This journey leads Ben and his crew not only to surprising revelations but to the trail of the worlds most treasured secrets. Ben follows an international chain of clues that takes him on a chase from Paris to London and ultimately back to America. Somebody uses a page from the diary of John Wilkes Booth to accuse Ben's ancestor.The synopsis below may give away important plot points.

National treasure book of secrets