21 Days of Fear: A Letters Thriller

Author: Herve Commere

Thrillers (Children's / Teenage)

Published on 24 September 2026 by Simon & Schuster Ltd in the United Kingdom.

Hardback | 422 pages
158 x 218 x 35 | 818g

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 has twenty-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 openA gripping missing-person mysteryDark family secretsTwists, clues and shocking revelationsA tense twenty-one-day countdownAn immersive reading experience perfect for fans of high-concept YA thrillers