Dr. Lily Houghton travels from London to the Amazon jungle and enlists wisecracking skipper Frank Wolff's questionable services to guide her downriver on La Quila, his ramshackle-but-charming boat. Lily is determined to uncover an ancient tree with unparalleled healing abilities, possessing the power to change the future of medicine. Thrust on this epic quest together, the unlikely duo encounters innumerable dangers and supernatural forces, all lurking in the deceptive beauty of the lush rainforest. But as the secrets of the lost tree unfold, the stakes reach even higher for Lily and Frank and their fate and mankind's hangs in the balance.