Alice (Danielle Darrieux), a widowed Frenchwoman, goes on a vacation to Italy. Upon her return, she relates the particulars of her holiday. Within a 24-hour time frame, Alice gets on the wrong boat, winds up in Switzerland where she whiles away the hours at a casino, meets a handsome young German army deserter named Thomas (Robert Hoffman), spends the night with her new acquaintance, pays his sizeable gambling debts, and helps him elude the authorities...