The spine-tingling new thriller from the Sunday Times bestselling author of The Chalk Man.

One night, Annie went missing. Disappeared from her own bed. There were searches, appeals. Everyone thought the worst. And then, miraculously, after forty-eight hours, she came back. But she couldn't, or wouldn't, say what had happened to her.

Something happened to my sister. I can't explain what. I just know that when she came back, she wasn't the same. She wasn't my Annie.

I didn't want to admit, even to myself, that sometimes I was scared to death of my own little sister.