The plot of "Paper Moon" culminates in a series of events that test the bond between Moses and Addie. After their successful cons, their partnership is threatened by the arrival of Trixie Delight, a carnival dancer Moses becomes infatuated with. He spends their money on her, including buying a new car. Seeing Trixie as a threat, Addie conspires with Trixie's maid, Imogene, to expose Trixie's promiscuity. They set up a situation where Moses walks in on Trixie with a hotel clerk, leading a disgusted Moses to abandon her.
Their success is short-lived. They run a bootlegging con where they steal whiskey and sell it back to the bootlegger. However, the bootlegger's twin brother is the local sheriff (both roles played by John Hillerman). Though they initially escape, the sheriff and his deputies later catch up with them across the state line in Missouri. Since they are out of their jurisdiction and cannot arrest him, they brutally beat Moses and steal all of his and Addie's money.
Defeated, broke, and humiliated, Moses finally drives Addie to her aunt's house in St. Joseph, Missouri, fulfilling his original promise. He gives her the photo she had taken of herself on the paper moon at the carnival and leaves her on the porch. The seemingly inevitable, 'proper' ending has arrived. However, as Moses drives away, he sees Addie running after him down the road. She tearfully confronts him, yelling that he still owes her $200. As they argue, his truck begins to roll away down the hill. Addie points it out, and as Moses scrambles to catch it, she climbs in. The final shot shows them driving off together down the long, empty road, their partnership restored. The ending reveals that the bond they formed is more powerful than the promise of a stable, conventional life for Addie. She chooses the 'make-believe' world with Moses, making it her reality.