Marie-Laure lives with her father near the Natural History Museum in Paris. When Marie-Laure is six years old, she goes blind and her father builds her a perfect miniature of the neighborhood. When Marie-Laure is 12, the Nazis occupy Paris and father and daughter flee to walled Saint-Malo. Carrying with them the museum's most precious and dangerous jewel.

In a German mining town, orphan Werner grows up with his sister and becomes obsessed with a crude radio they find. Werner becomes an expert at building and repairing this important new piece of equipment, and his talents lead him to the cruel academy for the Hitlerjugend, where he is later given a special assignment to track down the resistance. Werner, keenly aware of the cost of espionage, travels through the fires of war and finally arrives in St. Malo.