Pirate Island resumes the story of Elizabeth, a Planter in Nova Scotia in the 1760s. She and Mathilde, the daughter of the Acadian family Elizabeth helped in Book One, have become fast friends. But Sarah Worth is also Elizabeth's friend now, and Elizabeth hopes Sarah and Mathilde will learn to like each other. She wants the three of them to explore Pirate Island like her hero, Robinson Crusoe. After all, an adventure—including a search for treasure—should be just the thing to bring three girls together.