An unwieldy, cluttered, but superbly original and at times painfully intense addition to the Sime/Gen series, following House of Zeor (1974) and Unto Zeor, Forever (1978). The human species has mutated into Gens, who secrete an energy-field, ""selyn,"" and Simes, who need selyn to survive (and amplify their mental powers). Ercy Farris, daughter of and successor to Digen Farris, head of House Zeor, is on the threshold of maturity; absorbing her first selyn from mysterious, sympathetic donor Hal Grant, she becomes a talented Sime ""channel,"" one who can accept and transfer selyn without killing the Gen donor. Digen himself, believing his imposed constraint against killing donors dissolved, has not functioned as a channel for over 20 years; to cure him of this condition, Ercy is breeding mahogany-colored trinrose flowers, from which she hopes to extract a suitable drug. But her methods are unorthodox, and ambitious cousin Rellow accuses her of witchcraft--a charge which Ercy finds difficult to deny since she is now producing various uncontrolled paranormal phenomena. Only Hal can help her, by removing the constraint that is forcing Ercy's astonishing new selyn-using abilities into dangerously unpredictable pathways. Fascinating twists, convincing characters--but the fantastically involved Sime/Gen relationship and its terminology hinder rather than aid comprehension, sometimes proving a cumbersome drag on the narrative. Often spellbinding work, then, to be avidly devoured by existing Sime/Gen fans; anyone trying to break into the series at this point, however, will find it a struggle most of the way.