The knowledge gained in the Repository directs Aderyn, Owen, and their team to the distant, lawless city of Obsidian, in search of the next clues to the Fated One quest. Obsidian is dangerous for low-level adventurers, and the overland journey through monster-infested wasteland takes months. When they learn of a dungeon called Gamboling Coil that can transport adventurers instantly anywhere in the world, they leap at the chance. But nothing in the dungeon is as it seems, and it will take all the team's skills to make it out alive.

However, Gamboling Coil is only the first step. Obsidian's black walls harbor criminals, outcasts, and warring factions. An entanglement in city politics, and an encounter with another Warmaster, may prove more deadly than the worst monster the team has ever faced.