Liesl lives in a tiny attic bedroom, locked away by her cruel stepmother. Her only friends are the shadows and the mice—until one night a ghost named Po appears from the darkness. That same evening, an alchemist's apprentice named Will makes an innocent mistake that has tremendous consequences for Liesl and Po, and it draws the three of them together on an extraordinary journey. From New York Times bestselling author Lauren Oliver comes a luminous novel that glows with rare magic, ghostly wonders, and a true friendship that lights even the darkest of places.