Young medusa Ria turns an entire village of innocents to stone with her gaze. She flees with her older sister for the underground city of Nelroote, where Manticura’s quasi-fantastical sapient races—Scereans, Tuyuns, Feleenese, Cayanese—live on the margins. There she takes up her role as gatekeeper, protecting the city from threats, Human or otherwise.
Decades later, Manticura is now a modern urban city-state, and Eedric Shuen is bored with his privileged life. He stumbles upon the entrance to Nelroote and encounters Ria, who has spent nearly half a century in solitude. As their friendship blossoms, external whispers of the medusa sisters threaten to spark a chain of events that will throw Nelroote and its inhabitants into imminent danger.