Synopsis: From the back cover of the Ace first edition: "In the turbulent world of the twenty-first century, everything is rationed, everything is controlled. Crime still exists - and punishment is swift and severe. But on Black River a new breed of killer is lurking, one that this tortured future may have brought into being... "Red Sky at morning - sailors take warning" turns out to be all too true for the men of the river cutter Delora. When the crimson dawn breaks, one of them will dire before the next day, throat slit, ears missing. District Marshall Ty Merrick and her partner LaRue are called in to find out who is killing the crew. Who - or what. For the pollution that is an everyday fact of life in Ty's world has bred strange and dangerous monsters in the toxic waters of the Black River. It will take all of Ty Merrick's considerable detecting skills - plus her first-hand knowledge of monsters - to find the murderer before the red sun rises again..."