Riviere (John Barrymore), who operates an air delivery service, is fanatical in his dedication to service, putting prompt delivery before the safety of his men or his fleet after receiving a contract to help transport the mail. Riviere's risk-taking earns him the contempt of his pilots, including Jules (Clark Gable), who, despite his misgivings, does his best to satisfy Riviere's punishing schedule. When Jules is lost after a dangerous mission, Riviere has to tell his wife (Helen Hayes) that her husband has died, but despite losing another pilot (William Gargan), Riviere responds by demanding that more pilots be called up to ensure that the letters will be delivered on time.