Aboard the Astralaceae, Haledon's purpose was simple: to maintain the balance of nutrients that kept the bramble ship floating through space and seeding planets. Or it would have been if not for the sudden arrival of Druids from Earth and their delivery of a reality-altering truth: The Mecharrion stalk the abyss.

With the aid of Sparrow, a Primeval Druid of Earth and creator of the floral fleet of Astralaceaes, Haledon must bear the responsibility of preparing his peaceful ecosystem for war against a relentless, mechanical horror. With the help of his Guild--a motley crew of Druids, an Arbornaut, and a Therianthrope--Haledon will learn the fundamental principles of Druidic Culture to become a Master of Succession. But the Guild will face challenges from Druids and the Mecharrion alike over their training.

Will this Guild adapt the Astralaceaes in time to combat the deadly, mechanical foe that stalks the stars, or will their million-year mission come to a climatic end?