The story takes place on a night in August, at a small 24-hour supermarket. The boy Li Junwei is a night-shift clerk at the supermarket. Though he appears quiet and reserved, he has secretly developed feelings for his colleague Tang Xiaolian. Tonight, they are working together on the night shift. In Junwei's eyes, tonight should have been a romantic night, but it was disrupted by a man named He Sanshui.
Two months ago, He Sanshui bought a lottery ticket at the supermarket and won a prize of 9500 yuan. However, due to a numerical error made by the supermarket owner's wife, he lost his prize money. After multiple unsuccessful arguments with the owner's wife, He Sanshui returned to the supermarket tonight with his foolish nephew, Tire, determined to reclaim his prize money. Unable to contact the owner's wife, Li Junwei and Tang Xiaolian were unable to resolve the matter. In frustration, He Sanshui made a strange decision—he would openly stay in the supermarket, waiting for customers to buy goods so that he could accumulate the money he believed belonged to him. Due to their disagreement with He Sanshui's actions, both Xiaolian and Junwei's friend Zhu Liao were locked up in the office. Concerned about Xiaolian and Zhu Liao's safety, Junwei had no choice but to cooperate with He Sanshui and continue operating the supermarket.
Subsequently, various customers entered the supermarket. Because of He Sanshui's stubborn temperament and lack of familiarity with supermarket operations, many funny and amusing incidents occurred during the shopping process. Fortunately, Junwei was present to defuse the situations in time, allowing He Sanshui's plan to proceed. Meanwhile, Zhu Liao and Xiaolian, who were locked in the office, tried every possible way to escape, only to find each method causing Zhu Liao great suffering. Just as things in the supermarket were calming down slightly, the owner's wife Wang Sufen arrived. Upon meeting He Sanshui, the two clashed fiercely, almost turning the supermarket upside down. Ultimately, in desperation, He Sanshui locked Wang Sufen up as well.
As the long night dragged on, just when He Sanshui was finally close to accumulating 9500 yuan, an angry robber appeared in the supermarket. A week ago, a robbery occurred at a mall near the supermarket, where a priceless diamond was stolen. The criminal, while fleeing, hid the diamond in the supermarket's freezer to evade the pursuing police. Tonight, the robber returned to retrieve the diamond. Facing danger, everyone began brainstorming ways to collectively deal with the enraged robber, but due to poor coordination, many jokes ensued. Just as the robber was about to get the diamond and leave the supermarket, the police finally arrived in time. Desperate, the robber suddenly took Xiaolian hostage. At the most critical moment, encouraged by He Sanshui, Junwei came up with a brilliant plan. Everyone united together, cooperating with the police outside, to subdue the robber. Finally saved, as they stepped out of the supermarket, the sky was already brightening with the dawn.