One day, Noah Keller's ordinary American life is totally overturned when his parents reveal his name isn't actually Noah and that they are taking him to live in East Berlin, behind the Wall. Secrets become deadly. Surprisingly, Noah makes a new friend, Cloud-Claudia, the girl downstairs who lives with her mean grandmother and who has a love for codes and puzzles. Together, Noah and Cloud-Claudia try to find their way in their dangerous, walled new world.