“Wasp's job is simple. Hunt ghosts. And every year she has to fight to remain Archivist. Desperate and alone, she strikes a bargain with the ghost of a supersoldier. She will go with him on his underworld hunt for the long-long ghost of his partner and in exchange she will find out more about his pre-apocalyptic world than any Archivist before her. And there is much to know. After all, Archivists are marked from birth to do the holy work of a goddess. They're chosen. They're special. Or so they've been told for four hundred years.
Archivist Wasp fears she is not the chosen one, that she won't survive the trip to the underworld that the brutal life she has escaped might be better than where she is going. There is only one way to find out.” Plot overview from Amazon.com
A futuristic post-apocalyptic ghost hunting book? Sign me up!