Part One: Out of her orbit sped the teeming Earth-a marauding planet bent on starry conquest. Part Two: Deep in the gnome-infested tunnels of the Moon, Sarka and Jaska are brought to Luar, the radiant goddess against whose minions the marauding Earth had struck in vain. Part Three: Martian fire-balls and the terrific Moon-Cubes wreak tremendous destruction on helpless Earth in the final death struggle of the warring worlds. This book originally appeared as a 3-part serial in Astounding Stories of Super-Science in July, August, and September 1930.