The Knights of Gummadoon

"The Knights of Gummadoon" is the twenty-eighth episode of the Adventures of the Gummi Bears which aired on December 5, 1987.

Plot
When the castle of the knights of Gummadoon appears, Cavin is imprisoned as a spy. The Gummies only have until sunset to rescue him, as the castle only appears once every hundred years, but they also have to contend with Duke Igthorn, who plans to capture the castle.