Myfanwy Thomas awakens in a London park surrounded by dead bodies. With her memory gone, she must trust the instructions left by her former in order to survive. She quickly learns that she is a Rook, a high-level operative in a secret agency that protects the world from supernatural threats. But there is a mole inside the organization, and this person wants her dead.

Battling to save herself, Myfanwy will encounter a person with four bodies, a woman who can enter her dreams, children transformed into deadly fighters, and terrifyingly vast conspiracy.