The Catallax mobile relief mission is formally led by Sisters Justice and Mercy. Sister Justice, who served as a neutral during the armistice negotiations, now aims to bring law and order to criminal space, with a natural authority that even hardened pirates have come to respect. Sister Mercy, one of the most accomplished ministers during the War, hopes to redeem even the worst of the worst by evangelizing the Catallax way. But who is the Passenger, and what to make of the whispers that he has an agenda of his own?

The Catallax crew consists of scientists, mediators, and aid workers. The Catallax survive among the pirate crews by avoiding hostilities, both through negotiation and stealth technology. Yet cynics among the other pirate crews wonder why the Catallax always seem to be turning up where the finds are, whether the Catallax charitable mission is hiding technology to let them loot and smuggle undetected.