The Rook by Daniel O’Malley [Book]
The body you are wearing used to be mine.
So begins the letter Myfanwy Thomas is holding when she awakes in a London park surrounded by bodies all wearing latex gloves. With no recollection of who she is, Myfanwy must follow the instructions her former self left behind to discover her identity and track down the agents who want to destroy her. Set in an alternate London, Myfanwy discovers that her former self was/is a high-ranking officer of the secret organization, the Chequy, which battles supernatural forces in Britain. She quickly scrambles to (re)learn her job, while trying to figure out who in the organization wants to kill her. The character of Myfanwy is wonderful, and she handles her unusual situation with a wry wit.