In this story, a sixty-six-year-old retired arithmetic teacher decides to take a hot-air balloon trip around the world in an effort to get away from everyone. Halfway around the globe, however, he becomes stranded on a volcanic island that is about to experience a massive eruption. The fantasy of The Twenty-One Balloons is built around an actual historic event—the massive volcanic eruption that destroyed the Pacific island of Krakatoa in 1883. But there the connection with history ends. The Professor discovers that the inhabitants of the island have established a unique, Utopian society, which he seeks to understand. Threatened with destruction, the Professor and the inhabitants must cooperate and discover a way to escape the island before the final explosion.
Humor, social vision, fantasy, and realism combine in this multi-layered narrative. The captivating, period-style illustrations by the author add a further dimension to the reader's pleasure.