A chilling YA thriller told through 21 sealed letters, with the suspense building day by day.

What would you do to bring your sister back from the dead?

After Lucas's sister mysteriously disappeared ten years ago, his family was torn apart. His mother has been lost in a deep depression ever since, his father has been unable to speak of what happened and Lucas has been trapped in his guilt . . . until he receives a note that changes everything.

Lucas hastwenty-one days to find out the truth about what happened to his sister, and save her life . if she really is still alive.

Every action is watched, every choice counted. Can he save his sister without losing himself?

Open one sealed letter each day and experience the mystery as a real-time countdown - or tear through all twenty-one, if you can't bear to wait.

What to expect:

• 21 sealed letters to open
• A gripping missing-person mystery
• Dark family secrets
• Twists, clues and shocking revelations
• A tense twenty-one-day countdown
• An immersive reading experience perfect for fans of high-concept YA thrillers