The murder of an Imperial diplomat takes Din and Ana into the heart of the Empire's Apothetik division where dissecting Leviathans has led to mental corruption that's no less deadly than the physical corruption Leviathan's spread in their wake. Their case appears to be a simple locked room mystery, except the man seems to have robbed a bank vault containing Apothetik secrets after the time of death. Ana has no trouble figuring out the murder, but untangling the vault theft leads Ana and Din deeper and deeper into the secrets of the Apothetik order responsible for the alterations of Imperial servants that keeps the Empire safe. Local politicians, diplomats, and even the Apothetiks themselves have embraced forbidden practices, all in the name of the greater good. To save everyone in the city and the Empire's pipeline of alterations, Ana must make full use of her own alteration and in the process reveal what she really is to Din.

The rotting city provides the perfect backdrop to this tangled mix of murder and fantasy with an edge of horror. Just offshore is the eerie Shroud where the Apothetik's delve into the dead Leviathan's and extract the parts needed for the alterations. If the protective Shroud should fail for any reason the city would drown in corruption. Everything is complicated by the local politics because this takes place outside the Empire in a kingdom scheduled by treaty to join it in a few years. Given the value of the city to the Empire the king says he wants to renegotiate and yet he avoids the Empire's diplomats. Investigating the robbery leads Ana and Din to the Apothetik order where they find that they have made secret use of an alteration that lets those working in the Shroud see the future. Din has the very dubious honor of going to the Shroud itself to interview those who might have insight into the crime which only leads back to the politics. 

The theme of corruption is prevalent in the world building, the characters, and the crimes themselves. Din was already thinking about transferring to another department, now that he's seen the true depths of Imperial service joining the Legion defending the wall sounds even better. However, now that Ana has demonstrated such trust in him and he's seen how much the Empire needs her can he really run away? I usually don't care for horror laced fantasy, but this one has really drawn me in. I'm not sure most people would even identify it as "horror", but there's something Lovecraftian about the world building. Whatever it is, the setting is both original and interesting which really stands out in today's fantasy genre.