Reuters Pictures
An undated handout shows the cover of "Across the Endless River," a book by author Thad Carhart. Carhart found the real-life story of Jean-Baptiste Charbonneau so riveting and improbable that he wrote a novel about it. "Across the Endless River," is set in the vastly different worlds Charbonneau inhabited -- the rough and ready U.S. frontier of the early 19th century and an aristocratic Europe recovering from Napoleon's wars.