In the sun-drenched locale of Beaumont-sur-Mer, situated on the picturesque French Riviera, British con artist Lawrence Jamieson smoothly captivates affluent women with his charismatic charm and clever tales of being a dispossessed prince. Assisted by his devoted manservant Arthur and a corrupt police officer, Andre, Lawrence skillfully dupes these naïve ladies out of their savings, all while claiming to support the freedom fighters of his homeland. However, his well-executed schemes are interrupted by the brash American hustler Freddy Benson, who boasts of his own meager conning successes.
Lawrence, unimpressed with Freddy's unrefined methods, arranges for him to exit the town. However, Freddy inadvertently sabotages one of Lawrence’s targets. It dawns on Lawrence that Freddy is, in fact, a con artist himself, and he resolves to mentor him in the art of deception. Although Freddy struggles at first, he quickly learns the tricks of the trade, leading the duo to devise a new plan involving Freddy's mentally challenged brother, a ruse to dissuade potential romantic interests after Lawrence has exploited their wealth.
Yet when Lawrence refuses to split the profits with Freddy, tension brews, culminating in a high-stakes wager: the first to con $50,000 from a selected mark wins, while the loser must vacate the town. Their target becomes Janet Colgate, the newly crowned "United States Soap Queen," who arrived from a soap company contest.
Lawrence applies his conventional strategies on Janet, but Freddy interjects, masquerading as a U.S. Navy veteran and psychosomatic paraplegic seeking $50,000 for treatment from the supposed psychiatrist Dr. Emil Schaffhausen. In a counter-move, Lawrence poses as Dr. Schaffhausen himself, suggesting treatment for Freddy if Janet pays him the money upfront. What ensues is an escalating series of hilarious pranks, with Lawrence tormenting Freddy as part of the faux treatment, and Freddy resorting to a fake suicide attempt to gain sympathy from Janet.
As conflict simmers, Lawrence finds himself in a sticky situation when a group of British sailors confronts him, angered by his treatment of Freddy. Unbeknownst to him, Janet has drained her wealth to assist Freddy, and her genuine compassion enchants both con men. The emotional turn prompts Lawrence to call off the wager, opting instead to avoid participating in Freddy's ploy to win Janet's heart.
As the tale unfolds, Lawrence reveals himself as a Royal Naval Reserve officer, much to Freddy's astonishment, effectively reclaiming control and earning Freddy's gratitude. Meanwhile, he sends Janet back home, entirely unaware of the schemes she's plotting next.
Upon her return to her hotel room, Janet reunites with Freddy, who remains true to his mischievous self. To everyone's surprise, she professes her love for him, strengthening their complicated bond. Meanwhile, Lawrence remains oblivious to this twist; instead, he focuses on mending the chaos Freddy has stirred. When Janet visits his villa, she tearfully confesses that Freddy has swiped the $50,000 meant for his treatment. In a show of gallantry, Lawrence offers her an equivalent amount, only for her to return it with a playful smirk.
The plot thickens when it’s unveiled that Janet is actually the notorious American con artist Jackal, infuriating Freddy and delighting Lawrence, who takes pleasure in having been skillfully outwitted. As the dust gradually settles, the former enemies find a common bond in their shared humiliation, setting the stage for future schemes.
Seven days later, Freddy and Lawrence find themselves at the villa once more, lamenting their losses until a new wave of wealthy tourists arrives, led by none other than Janet, who now presents herself as a high-stakes real estate agent. In an exciting twist, she divulges to Lawrence and Freddy that her latest undertakings have earned her a fortune – yet it is the thrill of duping them that remains her true delight. Unwittingly, Lawrence and Freddy are lured into this new con game, bracing themselves for the unpredictable cat-and-mouse escapade ahead.
