Josh Flagsmith is a brave, epileptic pirate boy who lives in the Guardian's House in the west of the Western Isles, where pirates and colonists live side by side. Born with visionary powers, Josh is chosen as the Pirate Guardian, and entrusted with the onyx Stone of Truth, which he uses to control his epilepsy. But when a cruel colonist dictator seizes power, and throws Josh's parents in prison, Josh has to escape, and sail to the island...