Four Edwardian children, Reggie, Elsie, Tom and Toodles, are transported to Systurthia (sister to Earth) a planet populated and ruled by children. They engage in various Ruritanian adventures, travels, captivity and escape, including a war between two noble factions. All very high-spirited and cheerful, with gorgeous full-colour plates by Tony Sarg. A modern reader may be a bit disturbed by the way the children, including the toddler Toodles, remain happily on Systurthia without a thought for their parents' presumable distress. The author dedicated the book to his mother.