During a weekend trip to Ocracoke Island, siblings Judy and Stink Moody take part in a pirate treasure-hunting game, in which various clues lead them to silver coins, or "pieces of eight," hidden across the island.
Uncle, who is a pirate, doesn't fit in with the other members of the yacht club, so he starts his own club, buys a treasure map, and ends up marrying a mermaid.