Eleven-year-old Noah has always lived in a mysterious house that grows larger every night. With only his mother and a robot-boy for company, he spends his days building devices for the city of Liberty. It's a place he's not allowed to visit-not since his father almost destroyed it. After discovering a hidden message, Noah sets off to find the notorious inventor. All Noah wants is to be happy and for his skill to be appreciated, and he's certain he'll find both at his father's side. With the help of a band of smugglers, he sails to the infamous island of Singe. But what he finds there is perhaps more terrifying than the mechanical monsters his father was banished for. And when Noah returns home, he accidentally leads his father's robot army to Liberty once more. Now, it's up to Noah to rescue the city-but to do so, he'll have to make a terrible choice.