While exploring near the South Pole Tommy Travers and James Dodd, of the Travers Antarctic Expedition, crash in their plane and are seized by a swarm of man-sized beetles. They are carried down to Submundia, a world under the earth's crust, where the beetles have developed their civilization to an amazing point, using a wretched race of degenerated humans, whom they breed as cattle, for food. The insect horde is ruled by a human whose fiendish mind now plans to lead his unconquerable horde of monster insects forth to ravage the world, destroy the human race and establish a new era-the era of the insect.