Camille is desperate to escape her home on colonized asteroid Vesta, journeying through space in a small cocoon pod covertly and precariously attached to a cargo ship. Anna is a newly appointed port director on asteroid Ceres, intrigued by the causes that have led so-called riders like Camille to show up at her post in search of asylum. Conditions on Vesta are quickly deterioratingfor one group of people in particular. The original founders agreed to split profits equally, but the Sivadier syndicate contributed intellectual property rather than more valued tangible goods. Now the rest of the populace wants payback. As Camille travels closer to Ceres, it seems ever more likely that Vesta will demand the other asteroid stop harboring its fugitives. With "The Four Thousand, the Eight Hundred," acclaimed author Greg Egan offers up a stellar, novella-length example of hard science fiction, as human and involving as it is insightful and philosophical.