After disrupting a meeting with a stuffy royal family, George accidentally trades places with the king's snooty monkey, Philippe. While Philippe puzzles Ted with his flawless manners, George travels to the castle where his fun-loving antics raise eyebrows and bring shy Princess Isabel out of her shell. In a comical bungle, Curious George accidentally gets swapped with an identical-looking Royal Monkey from a small kingdom. George believes he is visiting his dream theme park, Castleland, and cavorts in the somber kingdom. The stuffy Royal Monkey believes he is staying with Ted until it's convenient to return home. Before being un-swapped, George brings some chaos but mostly joy back to the kingdom, its princess, and her father the king. And Ted teaches the Royal Monkey to be more carefree.