A girl whose subconscious contains dangerous ancient knowledge finds her voice in this ';grippingemotionally resonant' (School Library Journal, starred review) middle grade sci-fi fantasy perfect for fans of Diana Wynne Jones and Scott Reintgen.

Is there safety in silence?

In the city of Danak-Tol, children known as codexes are chosen to safeguard echoesfragments of ancient knowledge too valuable to destroy but too dangerous to use. Forbidden to speak lest she accidentally release her echo, codex Delta lives a lonely life. Still, she knows she must obey the wardens' strict rules to keep her home safe from the vicious beasts, heretical Scrappers, and toxic blood storms that lurk beyond the city walls.

But when Delta breaks her vows to help a young girl escape a blood storm, she begins to have strange dreams, which lead her to question everything she knows to be true about herself and her city. To find answers, Delta must journey to the one place she most fears: the wasteland beyond the walls of Danak-Tol.

Together with her small but feisty mechanical companion Flick, Delta dares the perilous ruins of a long-abandoned skyship, the gullet of a ravenous sphincter worm, and even befriends a young Scrapper named Drii. But all these adventures only lead to more questions. What is the true danger that threatens her entire planetis it really her echo, or is it the silence that has imprisoned the truth for so long?