A space cruiser, in search of its sister ship, encounters beings descended from self-replicating machines.

In the grand tradition of H. G. Wells and Jules Verne, Stanislaw Lem's The Invincible tells the story of a space cruiser sent to an obscure planet to determine the fate of a sister spaceship whose communication with Earth has abruptly ceased. Landing on the planet Regis III, navigator Rohan and his crew discover a form of life that has apparently evolved from autonomous, self-replicating machines--perhaps the survivors of a "robot war." Rohan and his men are forced to confront the classic quandary: what course of action can humanity take once it has reached the limits of its knowledge? In The Invincible, Lem has his characters confront the inexplicable and the bizarre: the problem that lies just beyond analytical reach.