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-lost 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.

Isabel, once known as Wasp, has become leader of the fearsome upstarts, the teen girl acolytes who are adjusting to a new way of life after the overthrow of the sadistic Catchkeep-priest. They live in an uneasy alliance with the town of Sweetwater—an alliance that will be tested to its limits by the dual threats of ruthless raiders from the Waste and a deadly force from the Before-time that awaits in long-hidden tunnels. Years ago Isabel befriended a nameless ghost, a supersoldier from the Before-time with incredible powers even after death, and their adventure together in the underworld gave her the strength and knowledge to change the brutal existence of the Catchkeep acolytes for the better. To save Sweetwater, Isabel will have to unlock the secrets of the twisted experimental program from centuries gone by that created the supersoldier and killed his friends: the Latchkey Project. Latchkey continues the story begun in Kornher-Stace’s widely acclaimed Archivist Wasp, an Andre Norton Award finalist that was selected by Kirkus Reviews as one of the Best Teen Books of 2015.