The film begins in a lively bar where a man named Jeremy, played by Timothy Simons, anxiously awaits the arrival of his date, a stunning blonde woman. Instead of his expected companion, he is unexpectedly approached by the cunning con artist Penny Rust, portrayed by Rebel Wilson. Penny cleverly masquerades as the shy sister of the woman Jeremy is waiting for, claiming that her sister's embarrassment over her small breasts is preventing her from meeting him. In a twist, Penny almost convinces Jeremy to hand over money for her sister's cosmetic surgery.
However, things take a turn when another victim of Penny’s schemes shows up at the bar along with the police, causing her to hastily flee, eventually managing to conceal herself among trash bags that she cleverly disguises as part of her outfit.
Meanwhile, across the ocean in France, a Danish man named Mathias, played by Casper Christensen, encounters the enchanting Josephine Chesterfield, acted by Anne Hathaway, who is sitting alone in a bar. Mathias, eager to impress, offers to sell Josephine a valuable bracelet that belonged to his mother. Just as their conversation unfolds, they are interrupted by Interpol officer Brigitte Desjardins, played by Ingrid Oliver, who accuses Josephine of being an international thief who stole chips from an elderly gentleman. In reality, Josephine is a British woman posing as an unsophisticated American, cleverly employing her wit to outsmart unsuspecting men. She successfully manages to steal Mathias's bracelet, substituting it for a counterfeit version.
The narrative continues on a train journey to the French Riviera, where Josephine encounters Penny once again, who is launching another con, pretending that she needs to gather ransom money for her kidnapped sister. Impressed by Penny’s skills, Josephine becomes intrigued. Their paths intertwine as they cross each other’s strategies. Josephine, wanting to eliminate competition, tricks Penny into heading toward Port-au-Prince instead of her home turf.
Upon her arrival in Beaumont-sur-Mer, Josephine discovers that Penny has infiltrated the town under less-than-honorable circumstances by swindling a man named Gregor, played by John Hales. Using her cunning, Josephine orchestrates Penny's arrest with the help of Brigitte and the intended victim, Gregor, identifying her as the swindler. While Penny languishes in a cell, Josephine capitalizes on her misfortune by instilling fear of the Russian mafia in Penny, which pressures her to return home under duress.
Reluctantly returning, Penny seeks guidance from Josephine on how to refine her abilities as a con artist. With Josephine’s mentoring, Penny learns various techniques to exploit gullible men. Their first target is a Southern tycoon named Howard Bacon, played by Dean Norris. Using a cleverly devised ruse, Josephine coerces Howard into proposing marriage under false pretenses, introducing him to Penny masquerading as her hideous sister. After Howard departs in disgust, leaving behind an engagement ring, tensions rise between the two women. Feeling sidelined, Penny begins to doubt Josephine's intentions, fearing she might be a notorious con artist known as Medusa.
The rivalry intensifies as the pair engages in a bet to see who can successfully con a wealthy man first. They set their sights on a clumsy young app creator named Thomas Westerburg, portrayed by Alex Sharp. While Josephine aims to charm Thomas at a casino, Penny, adopting a guise of blindness, gains his attention with a sob story that pulls on his heartstrings. However, Thomas appears to be more naive than first assumed, prompting both women to devise their plans around him.
As they navigate their respective con games, personal emotions intertwine. Penny finds herself developing genuine feelings for Thomas, complicating her intentions as she wrestles with the guilt of conning him. Their rivalry takes on a more personal angle, leading to a series of comedic and harrowing encounters. In one particular evening, after a chaotic and revealing night spent together, they discover a twist of fate as Thomas reveals he is not who he claims to be, leaving both women doubting their own strategies.
As the story unfolds towards its conclusion, Penny and Josephine eventually find themselves working alongside Thomas, who reveals his own cunning plan. Grudgingly, they agree to form an unexpected partnership, despite the antics that have transpired. In a festive finale during Christmastime, they embark on a new caper, concealing themselves under a Christmas tree as part of another successful con, with Thomas now in tow.
Through a plot full of twists and turns, friendship and rivalry, and unexpected romances, the film brilliantly unravels the art of deception and the complexities of human relationships, culminating in a chaotic yet satisfying conclusion.
