Not content with having hollowed out the center of the Earth in his earlier novels At the Earth’s Core and Pellucidar , in The Moon Maid Edgar Rice Burroughs has his hero voyage to the Moon, which also turns out to be hollow and inhabited on the inside by human-like creatures. The hero and his companion have a series of adventures there, and discover both the sophisticated Va-gas and the malevolent Kalkars. Time passes, and we turn to following the hero’s descendants as they fight against an invasion of the Earth by the Kalkars. In these episodes, the American flag has become a holy totem, uniting the human rebels.

The Moon Maid was published in Argosy magazine between 1923 and 1925 as a series of three short novels, which were eventually combined into a single book edition in 1926. It was well-received by readers, and a number of critics consider it to be Burroughs’ best work of science fiction. Today it’s not as well-known as his Barsoom or Tarzan novels.