City of Ghosts

The third book in this gritty, sexy urban fantasy trilogy. If you liked the compelling characters in 50 Shades of Grey, you'll love the Downside Ghosts series. Rogue spirits and psychopomps are terrorising people, and now someone is planning to open the gates to the City of Ghosts and unleash the dead on humanity. Faced with her greatest challenge yet, Chess has to travel to the spirit city to finally lay all her ghosts to rest. Chess Putnam has a lot on her plate.
Mangled human corpses have started to show up on the streets of Downside, and Chess's bosses at the Church of Real Truth have ordered her to team up with the ultra-powerful Black Squad agency to crack the grisly case. Chess is under a binding spell that threatens death if she talks about the investigation, but the city's most notorious crime boss - and Chess's drug dealer - gets wind of her new assignment and insists on being kept informed.
If that isn't bad enough, a sinister street vendor appears to have information Chess needs. Only he's not telling what he knows, or what it all has to do with the vast underground City of Eternity. Now Chess will have to navigate killer wraiths and a lot of seriously nasty magic - all while coping with some not-so-small issues of her own. And the only man she can trust to help her through it all has every reason to want her dead.