Shortlisted for the Costa Children's Book Award and the Branford Boase Award
Nominated for the CILIP Carnegie Medal

A teenage spy. A Nazi boarding school. The performance of a lifetime.

Sarah has played many roles - but now she faces her most challenging of all. Because there's only one way for a Jewish orphan spy to survive at a school for the Nazi elite. And that's to become a monster like them.

They think she is just a little girl. But she is the weapon they never saw coming...with a mission to destroy them all.

"A pulse-pounding, pitch-black Nazi espionage thriller... Killeen sets a cracking pace - and pulls off the risks he takes with breathtaking panache." - The Guardian

"A riveting plot-driven thriller...Sarah's psychological journey is particularly compelling." - The Bookseller

"a thought-provoking and incredibly page-turning debut." - The Irish Times

"I found myself mesmerized by Sarah’s journey into a world of human monsters. Orphan Monster Spy weaves one heroine’s courage through a spectrum of darkness, and the effects resonate long after the final page." - Ryan Graudin, award-winning author of the Wolf By Wolf duology

"Deeply disturbing and chillingly good." - Elizabeth Wein, author of Code Name Verity