In the eternal darkness of the fungal realm of Ūmfalla, two women from different worlds form an unlikely bond and use their newfound powers to try and topple an empire.

In Ümfalla, only those with dark-bright eyes can see the way. A Wanderer with a forgotten past and a mechanical-arm named, MĒNA, is one of those few. When she rescues a woman named, RUTHY, who has fallen from Sky Tracer-an abysmal machine that transports stolen children over the dark land to be sacrificed-she is thrust into a fight against the warrior Reapers and magical Weirs for the very existence of the realm. The world-tree of the sunlit realm of Avernus looms large over the Spore Cloud that shrouds Ümfalla in eternal darkness. Through secrets and deception, RUTHY reveals that she is actually ARETHŪSA, the new Ruler of Avernus who can speak through the mycelium beneath the earth and directly to the Goddess who sleeps within the world-tree.