Killashandra Ree is a crystal singer, enabled by the symbiont in her bloodstream to heal rapidly and live without aging for centuries. The cost for this longevity is a lifelong need to cut crystal, a process that requires perfect pitch and slowly eats away at her memories. As Killa's memory deteriorates, a chance encounter with a mysterious substance plays a pivotal role in her future. Highly original world-building made this an interesting read.