Neffy is running away from grief and guilt and the one big mistake that ended her career. She decides to volunteer in a controlled vaccine trial -it offers her a way to pay off her debts and perhaps, to make up for the past. When the London streets below her window fall silent and all external communications cease, only Neffy and four other volunteers remain in the unit. Who, or what is out there? The long-awaited new novel from the Costa prize-winner, and Women's Prize short-listed author.