Regina Lampert (Audrey Hepburn) is a young Parisian woman whose husband has been murdered over stolen money, which a number of people think is now in her possession. Three shady characters (Tex, Scobie, and Gideon) are after the goods and her only ally (or is he?) is a handsome and mysterious man of many names (Cary Grant) who has taken an unexplained but welcome interest in her.