Science fiction, in a fantastic adventure story, a sort of modern Jules Verne, with adventure in the universe. Martin and Jane Ridley, twins, have exploring in their blood and yearn to travel to undiscovered places. By chance Martin learns of Professor Erdleigh's rocket to the moon project, and stows away with his sister in the first, test rocket. Their trip through space, their landing on the moon and what they find, makes exciting reading. They are ultimately rescued, of course, as their father and the Professor arrive on the second rocket. Mad as the story is, there is scientific fact behind it, and the style is clear and credible. The net result is good bridging for comic-book-minded-boys.