Upstairs, Downstairs at the French Riviera 1931. Jack, Frances and Uncle Sal are supposed to be the guests of honour at a dazzling New Year's party in Nice. But instead, their hostess needs their discreet help to solve the theft of government documents before it becomes public. With all their plans awry, Frances swaps her evening gown for a maid's uniform, Jack poses as chauffeur, and retired Vaudeville artist Uncle Sal intrigues the guest at the house party as a man of possibly nefarious mystery. With their suspects out and about, including nights at the casinos, it is difficult to keep track of their suspects without raising suspicion about their roles. Just when Jack and Frances think they've solved the theft, a death under palm trees raises the stakes. They need all their wits and ingenuity to unravel this tangled web and catch the murderer before a second victim dies ...