Seventy-five years from today, the human race has been cast from a dying Earth to wander the stars in a vast fleet of arks--each shaped by its inhabitants into a diverse and fascinating new environment, with its own rules and eccentricities. When her sister disappears while responding to a mysterious alien distress call, Eryn insists on being part of the crew sent to look for her. What she discovers on Candidate-623 is both terrifying and deadly....