A starship wins a massive space battle and arrives at Purth-Anaget, a planet orbiting a black hole. On the starship's hull, a crablike maintenance 'hardshell' robot who traded its original human form for immortality is forced by its programming to break rules in order to help Armand, an injured biological human found clinging to the side of its ship. As the hardshell helps the human heal, the two clash over their relative humanity. Armand believes only those who've retained their biological 'True Form' can be considered human. The hardshell believes anyone who originated from a human mind is human, and is angered by Armand's wartime choice to sacrifice numerous robot forms in battle as though they weren't human. Armand is determined not to be caught by the other hardshells, who would kill him for his crimes, so he offers the hardshell his entire fortune to help him escape to the surface of Purth-Anaget. The hardshell consults the Holy of Holies (a priest confessor) of its people for guidance. The Holy counsels that the hardshell should take the fortune, as it will divest Armand of his power and prevent him doing further harm to the hardshell population - in essence allowing a war criminal to live but stripping him of all his power. The Holy instructs the hardshell to follow Armand's instructions to the letter of the law and let him live - as the hardshell's programming demands - but find a way to mete out justice. With a tiny adjustment of the starship's trajectory as the Armand's escape pod ejects, the hardshell sends the pod skimming closer to the black hole than originally arranged, guaranteeing that it will take over four hundred relative years before Armand lands on the surface of Purth-Anaget, where he will be a relic, long-forgotten, and where the immortal hardshell, long since freed of the do-no-harm strictures of its programming, will be waiting for him.