Several British and American civilians, service members and United States Merchant Marine are stuck in a lifeboat in the North Atlantic after their ship and a U-boat sink each other in combat. Willi (Walter Slezak), a German survivor, is pulled aboard and denies being the U-boat's captain. During an animated debate, engine room crewman Kovac (John Hodiak) demands the German be thrown out to drown. However, the others object, with radioman Stanley (Hume Cronyn), wealthy industrialist Rittenhouse (Henry Hull) and columnist Connie Porter (Tallulah Bankhead), who speaks German, succeeding in arguing that he be allowed to stay. Porter, initially alone in the boat, had managed to bring her luggage with her, and her primary concern at first is a run in her stocking. She is thrilled at having filmed the battle between the two vessels, but her movie camera is the first in a series of her possessions to be lost overboard in a succession of incidents.