The young pirates-in-training list suspicious things in the port city of King's Island while running errands for Rotten Tooth, but he dismisses their concerns, leaving the "wee pirate kids" on their own to deal with strange events occurring on The Sea Rat after they return.

When, after finding buried treasure guarded by giant sand crabs, the crew of the Sea Rat comes down with a mysterious illness, the pirate students suspect that the treasure is cursed.

While spending a week on the Bone Rattler, a ship that is not exactly ship-shape, the pirates-in-training get stuck in Shipwreck Pass and must come up with a creative plan to save the Bone Rattler and find the treasure Captain Stinky beard seeks.