"Why do they call him Black Jake? Is it because of his hair?' Titty asked.""'Because of his heart' said Peter Duck." The Swallows and Amazons, as well as Captain Flint and the ancient able seaman Peter Duck, set sail on the "Wild Cat" bound for the Channel. But they are shadowed by the "Viper," manned by none other than Black Jake -- a beastly pirate with a dark plan. Can the children race ahead and uncover the buried treasure before the pirate? Can they survive storms, earthquakes, crabs and even a waterspout and make it home?