The magic tree house lands Jack and Annie on a deserted, tropical beach in the Caribbean of the 1700s. Their tropical setting quickly turns into a thrilling chase when they spot a rough-looking pirate ship and a group of scary, heavily-bearded buccaneers making landfall. They are searching for a missing treasure chest to help Morgan le Fay. Their adventure involves navigating the rugged island, avoiding the dangerous crew, and trying to recover the buried gold. They are eventually captured by the pirates and must use their wits and knowledge to outsmart the captain and his crew before they are forced to walk the plank. The siblings learn about the harsh realities and dangers of the high seas and pirate life before making a daring escape and finding the treasure.