A young girl inhabits an isolated island with her scientist father and communicates with a reclusive author of the novel she’s reading. It is an existence that mirrors that of her favorite literary character, Alex Rover, the world’s greatest adventurer. But Alexandra, the author of the Rover books, leads a reclusive life in the big city. When Nim’s father goes missing from their island, a twist of fate brings her together with Alexandra. Now they must draw courage from their fictional hero, Alex Rover, and find strength in one another to conquer Nim’s Island.

A shipping disaster in the 19th Century has stranded a man and woman in the wilds of Africa. The lady is pregnant, and gives birth to a son in their tree house. Soon after, a family of apes stumble across the house and in the ensuing panic, both parents are killed. A female ape takes the tiny boy as a replacement for her own dead infant, and raises him as her son. Twenty years later, Captaine Phillippe D’Arnot discovers the man who thinks he is an ape. Evidence in the tree house leads him to believe that he is the direct descendant of the Earl of Greystoke, and thus takes it upon himself to return the man to civilization.