Humanity played with fire once too often. It was atomic fire and its ravages produced an almost complete annihilation, but there were survivors. The radiations had not been entirely malevolent in their influence. Genes and chromosomes danced like dervishes in the gamma bombardments, and settled back into fantastic new patterns. God-like beings strode proudly athwart the devastation. Half-human demons lurked in the shadowy ruins. The twilight of humanity faded into a new heroic epoch, behind which the forbidden secrets of the ancient atom gods bided their time...