A serial killer has travelled across the Eastern Quadrant of the galaxy leaving a trail of mutilated corpes behind them. Galactic Council profilers predict the next murder will occur in the Black Systems, a haven for galactic criminals. With many of the established planetary leaders being bribed to ignore the criminal presence, they refuse to join the council and allow the Galactic Council's police force, known as the Guardians, jurisdiction. As planetary elections approach, systems president, Coalition Master Darl, wants to eject the alien criminal society and bring his people into the galactic alliance. Risking riots and electoral failure, he requests a guardian work undercover to find the killer. With Gaeizaan slaves once common in the Black Systems, and rumours persisting about some surviving a plague, it is agreed a guardian will come in under this guise. Space guardians from the quadrant being unable to undertake the mission in case of recognition, a Gaeizaan based guardian, Luapp Nostowe, is seconded to space duty. To help him with the mission he needs a female assistant to act as bait and draw the killer out. He chooses Enegene Namrae, a civilian he knows has the skills to protect herself. Due to history between them, Luapp and Enegene have a mutual wariness of other, but it doesn't stop them working together.