The Walker children - also known as Captain John, Mate Susan, Able-Seaman Titty and Ship's Boy Roger - set sail on the Swallow and head for Wild Cat Island. There they camp under open skies, swim in clear water and go fishing for their dinner. But their days are disturbed by the Blackett sisters, the fierce Amazon pirates. The Swallows and Amazons decide to battle it out and so begins a summer of unforgettable discoveries and incredible adventures.