Swaggering seaman Tom Wilder (John Wayne) comes to the rescue of Chinese villagers seeking to escape the yoke of communism. Persuaded by a missionary's daughter (Lauren Bacall) to undertake the task, the Duke reluctantly agrees to transport the group -- on an old paddle steamer -- through the hazardous Formosa Straits to safe harbor in Hong Kong. On a journey marked by peril, the determined band must outwit the fierce forces of the Red Menace.