"One Piece Film Gold" is the 13th feature film in the "One Piece" franchise, set in the New World era of the series. The story takes place on Gran Tesoro, a massive, independent entertainment city governed by the flamboyant and wealthy Gild Tesoro, a former slave who rose to power through his cunning and ambition. Gran Tesoro is a floating city of excess, where gambling, entertainment, and luxury are the primary attractions, but beneath its glittering surface lies a darker reality of exploitation and corruption.

The Straw Hat Pirates—Luffy, Zoro, Nami, Usopp, Sanji, Chopper, Robin, Franky, and Brook—arrive at Gran Tesoro, drawn by its reputation as a paradise. However, their visit quickly takes a turn when Nami is manipulated into gambling away the crew's treasure, leaving them indebted to Tesoro. To reclaim their fortune, the crew engages in a high-stakes heist to infiltrate Tesoro's vault, which holds unimaginable wealth. Along the way, they encounter allies such as Carina, a skilled thief with a personal vendetta against Tesoro, and Tanaka, a casino security officer with a unique Devil Fruit ability that allows him to phase through objects.

As the Straw Hats navigate the city's treacherous environment, they uncover Tesoro's true nature. His immense wealth and power are fueled by his ability to manipulate gold using the Gol Gol no Mi Devil Fruit, which grants him control over the precious metal. Tesoro's ultimate goal is to dominate the world by amassing enough wealth to buy the World Government itself. The Straw Hats, determined to stop him, confront Tesoro and his enforcers, including the formidable Dice, a gladiator with immense strength, and Baccarat, who uses her Luck Luck Fruit to manipulate fortune.

The climax of the film features a dramatic battle between Luffy and Tesoro, showcasing the latter's overwhelming power and the Straw Hats' resilience. Through teamwork and determination, the crew manages to outwit Tesoro and dismantle his empire, freeing the oppressed citizens of Gran Tesoro. The film concludes with the Straw Hats departing the city, their bonds strengthened and their resolve to continue their journey undeterred. "One Piece Film Gold" combines action, adventure, and themes of justice, offering a self-contained story that aligns with the broader narrative of the "One Piece" universe.