For over a hundred and fifty years, the rarest and most valuable substance in the solar system has been mined from the only location where it exists in significant quantity: Jupiter's largest moon, Ganymede. For all of this time, the remote mining outpost has been serviced by clone slaves who are drugged into mindlessness, and all of it has been monitored, controlled, and administered by the artificial intelligence known as Prinox.

But what happens when a failed rescue mission causes a small band of escaped clones to begin questioning their lives, their society, and their very existence? Hunted by deadly killing machines, confused and scared, these renegade slaves are about to find out—for better or worse—just what it means to be human.