Since Parisian girl Marie-Laure lost her sight, she has been living in her own world, either among the pages of books her father brings her or in the corridors of the National Museum of Natural History where he works. Captivated by the museum's wonders and the mythical stories about its collections, especially the mysterious jewel, the Sea of Flames, she spends her days with her father in her usual routine until the war forces them to flee, carrying a dangerous secret.

On the other side of the war, in an orphanage in a small German town, a German teenager spends his days with his little sister, fascinated by the magic of the radio and its ability to transmit news and stories from distant lands. Werner follows his obsession and becomes skilled in assembling and repairing radios until the war demands his expertise, and he joins the German army's engineering corps. Through their stories, Anthony Doerr tells a captivating tale about the goodness that can be seen despite the horrors of war and what war does to dreamers.