1916. Dreaming about saving countless lives and having another adventure, the feisty English feminist and doctor of botany, Dr Lily Houghton, embarks on a peril-laden mission to change the world. Along with her fashionable brother, MacGregor, Dr Houghton enlists the help of the arrogant, wisecracking riverboat skipper, Captain Frank Wolff, to guide them through the serpentine Amazon River in La Qu