A feisty young girl called Nim (Abigail Breslin) lives on a wild tropical island with her father and her best friends Silkie the seal, the crazy iguana Fred and Galileo the plucky pelican! Inspired by ancient legends and her favourite books penned by the reclusive author Alexandra Rover (Jodie Foster), Nim leads a wild and exciting life. Her literary hero, Alex Rover (Gerard Butler) is the world's greatest adventurer so when her island paradise is thrown into peril, Nim reaches out to her hero for help.