When Royal Air Force pilots are shot down over German-occupied France, they seek refuge in Paris. Once in the city, group leader Paul Lavallier (Paul Henreid) reconnects with his former teacher, Father Antoine (Thomas Mitchell), who shelters the fugitives and agrees to help them contact other Allies. While Lavallier attempts to elude a Nazi officer, he meets and falls for the beautiful Joan (Michele Morgan), but the young couple becomes imperiled when the Gestapo begins to close in.