J.-H. Rosny Aîné is the second most important figure in modern French science fiction after Jules Verne. Rosny, who was a member of the distinguished Goncourt literary academy, was also the first writer to straddle the line between mainstream literature and science fiction. Until now, Rosny has best been known to the English-speaking public for his prehistoric thriller, Quest for Fire. In The Cataclysm (1896), the physical laws of nature change in an entire region of France because of the arrival of a strange electro-magnetic entity from outer space.The Mysterious Force (1913) is about the destruction of a portion of the light spectrum by aliens who, for a brief while, share our physical existence. In Hareton Ironcastle (1922), explorers discover a mysterious alien world, fauna and flora, embedded in the Heart of Africa. This is the third in a series of seven volumes, six of which are translated and annotated by Brian Stableford, devoted to presenting the classic works of this giant of French science fiction.