Synopsis according to Goodreads:
“Death is no stranger in the city of Erisín– but some deaths attract more attention than others.
When a prostitute dies carrying a royal signet, Isyllt Iskaldur, necromancer and agent of the Crown, is called to investigate. Her search leads to desecrated tombs below the palace, and the lightless vaults of the vampiric vrykoloi deep beneath the city. But worse things than vampires are plotting in Erisín…
As a sorcerous plague sweeps the city and demons stalk the streets, Isyllt must decide who she’s prepared to betray, before the city built on bones falls into blood and fire.“