With the help of a young runaway, a feisty 14-year-old fights to keep her idyllic island home from the clutches of developers.

Return to Nim's Island to see how things are going with Nim and her Father. One day they get a message that some people will be buying the island to build an attraction there, but Nim will not stand for it and comes up with some things to do to save what she calls home.—Anonymous

Three years after the events in Nim's Island, the island faces a new challenge. The operators of the ship Buccaneer have gotten permission to develop a pirate resort on the island, and Nim (Bindi Irwin) and her father pursue separate plans to stop them. Meanwhile, a city boy named Edmund (Toby Wallace), who has met Nim once before and decides to see her again, has run away from home to the island, inadvertently bringing poachers with him. With her father, Jack Rusoe (Matthew Lillard) away on the mainland, Nim must learn to work with Edmund in order to save the island from the poachers.