[1][2][3] The book follows the story of Ash, a member of a sect of assassins known as Rōshun, who offer protection through the threat of vendetta, and Nico, who is a street urchin living in the city of Bar-Khos, which is under siege by the Holy Empire of Mann.

Their leader, Holy Matriarch Sasheen, ruthlessly maintains control through her Diplomats, priests trained as subtle predators.

Forced by his ailing health to take on an apprentice, he chooses Nico, a young man living in the besieged city of Bar-Khos.

When the Holy Matriarch’s son deliberately murders a woman under the protection of the Roshun; he forces the sect to seek his life in retribution.

As Ash and his young apprentice set out to fulfil the Roshun orders – their journey takes them into the heart of the conflict between the Empire and the Free Ports .