National Treasure: Book of Secrets(2007)
In 1865 after the Civil War, Thomas Gates and his son Charles Carroll Gates are approached by John Wilkes Booth and Michael O'Laughlen, both of them Knights of the Golden Circle. They ask Thomas, a skilled puzzle-solver, to decode a playfair cipher written in Booth's diary. O'Laughlen stays with Thomas as Booth leaves to assassinate President Abraham Lincoln. Just as Thomas discovers the message is a map to Cíbola, the fabled City of Gold, pandemonium arises in the streets from the President's assassination. Thomas realizes that Booth and O'Laughlen are still loyal to the South, tears the pages from the diary, and tosses them into a fire before O'Laughlen can shoot him. O'Laughlen only manages to save a partial page from the fireplace before escaping, while Thomas' dying words to Charles are "the debt that all men pay".
The film then shifts to modern day (140 years later), where Benjamin Gates, Thomas's great-great-grandson, is retelling Thomas' story at a Civilian Heroes conference. He and his father Patrick Gates are publicly accosted by Mitch Wilkinson, a black market dealer who has come into possession of the diary page, which appears to link Thomas to Booth and Lincoln's assassination. Ben determines to solve the puzzle on the page to restore Thomas' legacy.