The day after Pearl Harbor, Nick Browning leaves MIT to join the fight only to discover that a secret wartime agency appreciates his special skills. After two years working Europe’s dark edges for the Office of Special Services, Istanbul happens — and now Nick is damaged goods. Given an OSS desk job in Berne, he falls for Mariel Beauvais, a French Resistance fighter running Jewish children into Switzerland, and makes an extraordinary promise to Colonel Dieter Braun, a German officer based in Paris who wants to assassinate Hitler.

But when the plot fails, Braun must flee Paris with his pregnant French lover as the city explodes in bloody reprisals. Meanwhile, amid rumors of civilian massacres throughout the French countryside, Mariel chooses to gather what children she can and risk everything on one final run for the Swiss border. Across that border is Nick Browning, and Berne, and safety — but at what price, and who must pay it?