A mysterious man named Leland Gaunt arrives in the small town of Castle Rock, Maine, and opens a curio shop called "Needful Things." The shop attracts the attention of the townspeople, who are drawn to its unique collection of objects that seem perfectly tailored to their individual desires. Gaunt is no ordinary shopkeeper; he possesses a charismatic charm and persuasiveness that compel the residents to part with their money—and more. Customers find that he is willing to accept personal favors and small pranks in lieu of cash payment, leading to a deceptive sense of trust and indebtedness.

As the townspeople acquire their coveted items, they unknowingly enter into Faustian bargains with Gaunt. The seemingly harmless pranks gradually sow discord and escalate into violent confrontations among the townsfolk. Sheriff Alan Pangborn, skeptical of Gaunt from the beginning, starts to notice a disturbing pattern of animosity and chaos proliferating in Castle Rock. He becomes determined to unearth Gaunt's true motives while also trying to maintain peace and unravel the growing darkness overtaking the town. Meanwhile, Gaunt's influence continues to expand, revealing the depths to which the townspeople will sink under his subtle manipulations, testing the fabric of the community and the resilience of its inhabitants.