Adelheid Brunner does not speak. She writes and draws instead and her ambition is to own one thousand matchboxes. Her grandmother cannot make sense of this, but Adelheid will stop at nothing to achieve her dream. She makes herself invisible, hiding in cupboards with her pet rat, Franz Joseph, listening in on conversations she can't fully comprehend. Then she meets Dr Asperger, a man who lets children play all day and who recognises the importance of matchboxes. He invites Adelheid to come and live at the Vienna paediatric clinic, where she and other children like herself will live under observation. But the date is 1938 and the place is Vienna - a city of political instability, a place of increasing fear and violence. When the Nazis march into the city, a new world is created and difficult choices must be made. Why are the clinic's children disappearing, and where do they go? Adelheid starts to suspect that some of Dr Asperger's games are played for the highest stakes. In order to survive, she must play a game whose rules she cannot yet understand.