For exobiologist Cassie Clearwater, the chance to participate in an exploratory mission to Obsidian, a black, austere world rich in diamonds and occupied only by a mysterious species of plant, is the opportunity of a lifetime. The excitement deepens when she samples the indigenous lifeform and discovers that it emits copious quantities of complex chemicals. Her colleagues on the mission only care about diamonds, but Cassie yearns to discover how these plants thrive in such a dark and hostile environment.
In the society where young sprout Pepper lives, knowledge, wisdom, and memory are preserved in the thick trunks of the elders, whose growth rings go back thousands of years. The elders don’t appreciate the upstart Pepper, whose new ideas challenge ages-old wisdom, and they communicate their displeasure through the release of chemicals. But when members of the grove start disappearing with the intrusion of an unseen and undetectable force, Pepper’s penchant for original thought becomes the only hope for survival of the species.