Benjamin January, a librarian at the National Archives, receives a surprise visit from Clementine Kaye, an old childhood flame who is searching for Benjy's father. Trying to impress his old crush, Benjy gives Clementine a tour of a secret vault where classified documents are reviewed. There, the duo discovers a hidden dictionary that once belonged to George Washington and is plunged into a deadly mystery involving the most important secret in U.S. history.