The Enchanted Castle features a variety of minor characters alongside the major roles of the four youthful protagonists. The French governess who befriends the young people over their lonely holiday stay at the school also becomes a romantic heroine when the story of her seemingly hopeless love for an aristocrat is revealed. She is a delightful character, whose English is actually literalized French, which adds a comic touch to the story. Thanks to the children, her love story has a happy ending. The cockney policeman Johnson, another minor figure, is baffled by the antics of the young people, but is ultimately grateful to them for helping solve a burglary.

The four protagonists—Gerald, Jimmy, Kathleen, and Mabel—are distinctively drawn. Most important is the older boy, Gerald, who is a born leader with a habit of speaking of himself in the third...