Hardcover debut for the author of a couple of well-received science fiction paperbacks (Fool’s War, etc.). On planet All-Cradle live the Dedelphi, homicidal humanoid aliens whose numerous clans have been warring for millennia. Humans, however, are toxic to Dedelphi and must wear environmental suits. All active Dedelphi are female, powerfully bonded mother to daughter, sister to sister—except that when they grow old, they turn male. Now their technology has reached the nuclear and biological danger level: half the population has died from a mutated plague, and the desperate clans have ceased hostilities so that Dr. Lynn Nussbaumer of Earth’s Bioverse corporation can help. In return, Bioverse will be permitted exclusive access to the planet’s unexploited biological resources. The natives will be evacuated to huge orbiting city-ships while Bioverse deals with the plague. But Lynn finds that only wise Praeis Shin of the t’Theria clan is willing to negotiate a genuine end to the violence. Lynn, meanwhile, has a personal problem: old college flame Arron Hagopian has been working closely with the Getesaph clan and publishes some inflammatory material about Bioverse’s true intentions, claiming that it will sooner destroy the planet than let the clans fight it out. Then Arron discovers the Getesaph are planning a surprise attack on the first city-ship. He tries to warn Lynn but the Getesaph grab them both, along with Praeis’s daughter Resaime, who, having been deliberately confined with Lynn and Arron, quickly dies. The Getesaph capture the ship, the t’Theria retaliate, and war explodes across the planet. Even if Lynn can escape, how can she stop the carnage? A taut, thoroughly captivating yarn, with splendid characters, a gratifyingly substantial sociobiological base, and one intractable problem: Armed with nukes and missiles, how did the Dedelphi avoid exterminating themselves long before humans showed up?