will adapt only partly, with a mix of permanent symptoms such as vastly increased visual acuity along with complete deafness. Those who adapt fully to symbiotic life may become singers; other survivors must join the staff. The symbiont maintains its host, perhaps for hundreds of years, but only on Ballybran; only the fully adapted singers can safely depart, and only briefly. Full adaptation brings remarkable benefits, including increased sensory perception, rapid tissue regeneration and a vastly prolonged life expectancy, but it renders all hosts sterile, and eventually causes severe memory loss, paranoia and dementia. Even after full adaptation with the symbiont, mining Ballybran crystal is a dangerous occupation. Beside the risks associated with other mining operations, there are frequent storms with high winds that may cause crystal deposits to resonate: "sonic storms" that may impair the symbiont and drive the singer mad. The Guild provides life support for physically disabled or insane members, many aspects of the industry are highly centralized, and everyone begins with big debts. Yet singers in the field are solo adventurers who establish private claims, work them in secret, and sometimes amass great fortunes. Killashandra and thirty others accept the personal risks and make the commitment. The story follows her and her classmates in a general education program, awaiting infection. When her own adaptation is unusually rapid and easy, she advances alone to rapid acquaintance with the rules and customs, transport and cutting equipment, emergency procedures, commercial values, and some of the planet-bound specialists. She is especially sensitive to "black crystal", the rarest and most valuable variety. Partly for that talent, the Guild Master Lanzecki becomes her mentor (but soon her lover as well). Before any of her classmates learns to fly or to cut, she is in the field. She is first to find the unknown claim of a black crystal miner recently destroyed in a crash, and she cuts some of it adequately. Killashandra's rapid adaptation and training have isolated her from the other newcomers and her continued success has fostered jealousy, she sees even in her closest friends among the former classmates. So she accepts an assignment offered by Lanzecki, to install "her" set of crystals in a recently settled planetary system. The cost of a black crystal set is high, even on the planetary scale, which has made its acquisition politically controversial and its installation a celebrity event. Killashandra must not only