In the future life has spread to other worlds, but not human life. Very few human beings can survive space travel, so the zins were created.
Zins are three races of artificial life, nearly indistinguishable from humans. Because they are formed in factories, the zins’ need for raw material has always kept the planets dependent on each other for trade. Crawlships move goods and passengers from one world to another. The zins that crew the ships lead simpler lives, confined by the ship’s space and the gyre field that powers their craft.
It’s a life of routine, unless a tragedy strikes. On a long journey, Captain Bracer’s ship, the Meleera III comes to the aid of two distressed vessels. It soon becomes apparent that the other ships have been stopped deliberately, through sabotage. Someone is shutting down crawlships, and the Meleera III is the next target.