Ninth Tongue Of Dust

From publisher blurb:

In the labyrinthine gutters of Arnalm, Farnis, city of ash-colored silk and lanterns made from tanned skin, a thieves’ guild rots from within. Once the power behind the velvet masks of court, the Velhaim Blades now bicker, clawing at scraps while an unnamed terror festers beneath the cobbles. The city’s new Legat, Damar Vishera, promises stability — and yet his black-sailed barges arrive under moonless sky, unloading hooded monks and shrouded cargo. Disappearances spread like mold. Ancient murals are scrubbed clean in the name of order. And the thieves, who once ruled in shadows, are hunted like rats.

But one among them hears the whisper of deeper darkness. And in this whisper... an opportunity.