The magic tree house transports Jack and Annie to the Middle Ages, where they land near a magnificent, towering castle on a misty morning. Their mission is to find the next key for Morgan le Fay. They soon become trapped inside the fortress, where they witness a grand medieval feast, learning about the customs of lords and ladies. Their adventure takes a dangerous turn when they are forced to run through secret passageways and escape the castle's vigilant guards. They eventually encounter a kind, mysterious Black Knight who helps them evade danger and escape the castle before being captured. The trip teaches them about the age of chivalry, courage, and the life of a medieval knight before they return to the present.
