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. Zeth is the son of the first such channel, Rimon, and a Gen mother, and born into a community struggling to find a new way for both kinds of humanity to live together without killing each other. 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.