Mr. Bedford, who narrates the tale, tells of how he fell in with eccentric inventor Mr. Cavor, grew to believe in his researches, helped him build a sphere for traveling in space, and then partnered with him in an expedition to the Moon.

What they found was fantastic! There was not only air and water, but the Moon was honeycombed with caverns and tunnels in which lived an advanced civilization of insect-like beings. While Bedford is frightened by them and bolts home, Cavor stays and is treated with great respect.