A captivating Welsh folklore tale by Carnegie-nominated author Elen Caldecott, featuring a cover illustration shortlisted for Children’s Book Cover of the Year 2022.

Cassie’s older brother Byron has fallen in with the wrong crowd, but these aren’t ordinary boys. They’re tylwyth teg, the Fair Folk: wild, powerful, and not quite human. When Byron disappears, Cassie and her cousin Siân follow his trail to an old railway tunnel that leads deep into Annwn, the shadowy underworld.

There, they find the Fair Folk who are angry. Their leader, Gwenhidw, wants to protect Annwn from human destruction, and Byron is part of her plan. But Cassie won’t let her brother be used.

To save him, she must face ancient magic, uncover buried truths, and brave a world where nothing is quite what it seems.