What is the main conflict in Peter and the Shadow Thieves by Dave Barry?

Peter and the Shadow Thieves is a fictional story about an English boy named Peter who helps a secret organization known as Starcatchers escape from the sinister Lord Ombra, the leader of a dark group called The Others. Peter lives on the tropical Mollusk Island, which is inhabited by a band of pirates led by the evil Black 'Stache, also know as Captain Hook, as well as a band of natives called the Mollusks. He lives with four other boys on the island and is constantly accompanied by Tinkerbell, a fairy-like "birdgirl" who, like Peter, has the ability to fly.