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 appears from the darkness. It is Po, who comes from the Other Side. Both Liesl and Po are lonely, but together they are less alone.  
That same night, an alchemist’s apprentice, Will, bungles an important delivery. He accidentally switches a box containing the most powerful magic in the world with one containing something decidedly less remarkable. Will’s mistake 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 and magnificent story that glows with rare magic, ghostly wonders, and a true friendship that lights even the darkest of places.