Victor Hemsley and his daughter, Clare ply their trade at swanky Riviera resorts, where they pose as a married couple---hence the title---and he "disappears with all of her savings" and sympathetic money contributions pour in on her from the wealthy guests. She would prefer a more settled life and meets and falls in love with Terence Winch, an investigator for the British Treasury. He is ostracized by both the guests and the management as his job is to see that none of the British citizens spends more money than permitted by the government. Clare agrees to work with her father on one last scheme in which they "sell" the hotel they're staying in in Nice. They pull it off, but are paid in counterfeit money and flee to Italy, followed closely by the police and Terence. James Hayter appears as the wealthiest man on the Riviera who is also England's best known tax dodger, while David Hurst is a petty thief who always fails and Charles Goldner is an amorous hotel manager.