In 1940 New York City, a man known as Kid Colors (Burt Remsen) is tortured and killed as retribution for his role in swindling $500,000 from Doyle Lonnegan (Oliver Reed), a crooked banker from Philadelphia, Pennsylvania. His lead henchman, Carlos (Jose Perez), spreads the rumor that Brooklyn, New York, nightclub owner and pimp Gus Macalinski (Karl Malden), known as "the Wolf" for his reputation as a womanizer, is responsible for the Kid's killing, while Lonnegan plans the murder of confidence man Jake Hooker.Elsewhere in the city, con artist Jake Hooker (Mac Davis) and his friend, Eddie (Ron Rifkin), attempt to swindle Countess Veronique Le Fleur (Teri Garr) and her companion, Lady Dorsett (Frances Bergen), who turn the tables on them. Jake receives a telegram from his old con artist friend, Fargo Gondorff (Jackie Gleason), inviting him to Florida. After boarding the train, Jake and Eddie raise train fare by stealing off-duty police officer Francis O'Malley's wallet. Meanwhile, Carlos trails the two men and informs Lonnegan of their plans.After arriving in Miami, Florida, Jake and Eddie discover that Fargo is serving a two-year sentence in a federal prison and will be released within a few days. Fargo tells them about Kid Color's murder, placing blame on Gus Macalinski. A few days later, the three men return to New York City and meet with business associates "Handicap," (Larry Hankin) "Big Ohio," (Michael D. Alldredge) "Doc Brown," (John Hancock) and "Tuxedo" in the back room of a Chinese laundry, where they concoct a "sting" to cheat Macalinski out of a fortune. While Fargo establishes headquarters at Golding's gymnasium, Jake purchases boxing equipment at a department store, where he encounters Countess Veronique Le Fleur. Jake accuses her of being a pickpocket and alerts the store manager, who discovers O'Malley's wallet in the countess's handbag, and her coin purse in Jake's pocket. After both are ejected from the store, the countess introduces herself as Veronica Sherman... a con artist herself. Jake is sufficiently impressed with her skills and offers her a job as a member of the team to exploit Macalinski's weakness for the opposite sex.The next day at Golding's Gym, Jake receives his boxing license and his alias, Bobby Florian. He tells Fargo about Veronica, sheepishly revealing that she "reverse conned" him two weeks earlier. At Fargo's urging, Veronica admits to her real surname, Crinklaw. The next evening, she enters Macalinski's Ocean Club and draws the owner to her table. Fargo appears within seconds and introduces himself as Trevor Plantagenet. Veronica, who calls herself Elizabeth Windsor, pretends to be enamored with Fargo. He opens a bottle of champagne and the spray removes Macalinski's toupee. Attempting to overcome his humiliation, Macalinski challenges Fargo to a game of pool, then to a game of Three Card Monte. Fargo wins both, and Macalinski leaves the club in a fit of anger.Outside, Jake tells Macalinski he has information on "Trevor Plantagenet." Macalinski invites Jake, posing as "Bobby," to join him for a roller coaster ride. As the coaster speeds along the track, Jake explains that Fargo is his manager, and wants him to intentionally lose his upcoming fight against boxer Chico Torres. Jake intends to win the fight, and asks Macalinski for protection against a reprisal from Fargo in exchange for half of the $6,000 prize. After Macalinski promises to consider the offer, Jake encounters O'Malley. He eludes the officer and takes refuge in the Chinese laundry, where Fargo and his team are waiting for him. Fargo assures Jake that Macalinski will accept the offer, and advises him stay in hiding to avoid O'Malley. When Carlos updates Lonnegan on Jake's activities, the banker happily anticipates the murder of his adversaries by Macalinski.Meanwhile, Jake trains with Big Ohio, but shows little promise. However, when Macalinski visits the gym, they stage a sparring match and Jake knocks Big Ohio out of the ring. That evening, Jake informs Macalinski that Fargo is betting on Torres, and has arranged with bookmaker Tuxedo to increase the odds of Jake winning to attract more bets. Though Macalinski is intrigued, he refuses to commit until he sees Jake fight a professional boxer, which he arranges for the following day at the 8th Street Gymnasium. Jake leaves the meeting and evades O'Malley a second time. Carlos intercepts the policeman and takes him to see Lonnegan, who pays O'Malley to leave Jake alone until the sting is completed.After learning of Jake's dilemma, Fargo devises a plan to evacuate the gym, staff it with his own people, and drug Jake's competitor. When Jake wins, Macalinski agrees to protect him, and places a $400,000 bet with Tuxedo. Jake returns to Golding's and has a romantic interlude with Veronica. Confident of a victory by Torres, Lonnegan bets $1 million with a bookmaker named King Rafferty. Lonnegan directs O'Malley to the Chinese laundry, where he is expected to kill Jake and Fargo if Macalinski fails. The banker also introduces O'Malley to his informant, Samantha Scanlon, alias Veronica Crinklaw.On the night of the boxing match, Fargo instructs Jake to feign defeat in the sixth round, although Jake doubts he will last that long. While the fight is underway, Lonnegan informs Macalinski that Torres is the predetermined winner. On their boss's instructions, Macalinski's thugs reassign the bet to Torres and bring Tuxedo to the stadium at gunpoint. Believing their friend's life is in danger, Fargo instructs Jake to knock out Torres in the sixth round. Jake wins, despite his self-doubt, and is equally puzzled by Veronica's sudden absence. Fearing revenge from Macalinski, Lonnegan and Carlos run from the stadium, only to be ambushed in their car. O'Malley leads a police raid on the Chinese laundry and is greeted by a messenger, who delivers a bouquet of flowers and a derisive message from Fargo.On their way to the train station, Fargo explains that he hired Veronica to infiltrate Lonnegan's gang several months earlier. King Rafferty and Torres are also members of the organization. Fargo and his team board a westbound train, but Jake waits on the platform, hoping for Veronica's arrival. Moments after leaving the station, the train stops and Veronica disembarks. She tells Jake that she will be taking care of him from now on, as instructed by her father, Fargo.