War-time blackouts and U-boats skulking along the Atlantic seaboard brood over a New York City evening in 1943. Play rehearsals gone sour, actress Jessica Minton seeks her favorite diner for refuge. It proves anything but when an attractive stranger leaves her with a mysterious package. That's when Jessica is whirled up in treachery, treason, and murder, made even more dangerous by a suspicious boyfriend and her growing feelings for the stranger behind her predicament. Aided by her tart-tongued sister, a wise-alec cat, and her own wit and humor, Jessica tries to stay on top of a slippery espionage gambit that risks not only her life but the Allied cause.