IN THE WALLS OF ERYX was written in collaboration with Kenneth Sterling and first published in the January 1939 issue of Weird Tales.

Set on Venus, the story is presented as the recovered account of an Earthman employed by a mining company to harvest valuable crystals sought after for their energy properties. While exploring the Venusian jungle, the narrator becomes trapped inside an invisible maze-like structure—an alien construct built by the planet’s native, reptilian inhabitants.