Twelve-year-old Alexa Daley is spending another summer in Bridewell with her father. She looks forward to exploring the old lodge where she stays each year, with its cosy library and maze of passages and rooms. She's also eager to finally solve the mystery of what lies beyond the immense walls that protect Bridewell and the towns nearby. Legend has it the walls were built to keep out an unnamed evil that lurks in the forests and the Dark Hills - but what is it the townspeople are so afraid of?
