In the country of Ossaniul, there is a fortress that is as disproportionate as it is inaccessible: the Highest House. Its masters, the noble family of Aldercrest, reign over a veritable army of slaves. At the bottom of the ladder, young Moth performs the most thankless tasks and has little hope of living past childhood. Until the day he meets Obsidian, a mysterious prisoner of the House who whispers to him in his sleep. If Moth does what he asks, Obsidian will give him fortune and glory. And there's every indication that Obsidian can make good on his promises. Will Moth accept the offer?