Marie-Laure lives with her father in Paris near the Museum of Natural History where he works. When she is six, Marie-Laure goes blind. When she is twelve, the Nazis occupy Paris, and father and daughter flee to the walled citadel of Saint-Malo, where Marie-Laure's reclusive great uncle lives in a tall house by the sea. They carry with them perhaps the museum's most valuable and dangerous jewel.
In a German mining town, an orphan named Werner grows up with his younger sister, enchanted by a crude radio they find. He becomes expert at fixing these new instruments, a talent that wins him a place at a brutal academy for Hitler Youth, then a special assignment to track the Resistance. Increasingly aware of the human cost of his intelligence, Werner travels through the heart of the war and, finally, into Saint-Malo, where his story and Marie-Laure's converge.