In the far future a mutation develops and humankind is split into Simes and Gens. Simes "change over" at adolescence into vampire-like creatures that must suction off energy from Gens every month. Ordinarily, this causes the death of the Gen. But then "Channels" are discovered who could safely take energy from Gens and give that energy to Simes. But there are still "Sime" territories where Gens are kept like cattle, and "Gen" territories where a developing Sime would be shot on sight. Zelerod is a Sime who has predicted that the demographics mean that eventually if Simes continue their lifestyle there won't be enough Gens to keep them alive and civilization on both sides will collapse. Channels Klyd Farris from House of Zeor and Risa Tigue of Ambrov Keon team up to avert that collapse. Not my favorite of the Sime/Gen books--that would probably be Ambrov Keon--but definitely a good read in a series that's a favorite of mine. Both Lichtenberg and Lorrah who write books in this series and wrote this book together are both good storytellers and create characters to care about. And since each book was written to be read independently, this one can stand alone. ( )

In the far future, the human race is divided into Sime and Gen, just as it is into male and female. Simes must take energy from Gens each month to live, but when they do so, the Gen usually dies. Can they learn to live together without killing before the human race is destroyed? Fascinating, detailed, and focused on character relationships, I can't recommend these books enough. They are my all-time favorites. ( )