The story begins with the narrator introducing Mathilde Loisel, a beautiful and charming young woman who longs for a life of luxury. However, Mathilde does not come from money and therefore has few prospects. She marries Monsieur Loisel, a plain man and a clerk from the Ministry of Public Instruction. Together, they live a modest life, devoid of extravagance and opulence. As a result, Mathilde is fiercely unhappy and suffers greatly. She feels tortured by her worn-down surroundings and fantasizes about an elegant, upper-class life. Despite their financial struggles, Loisel is a good man and a devoted husband who works hard to make his wife happy. One evening, he prepares dinner for Mathilde, but she can only dream of the lavish dinners and extravagance she might have experienced in a wealthier life. She mourns her lack of affluence and more than anything, agonizes over her lack of jewels and fine clothing. Above all else, she longs to be admired and wanted.
One day, Loisel brings home an invitation to a party at the Ministry, expecting Mathilde to be delighted. He went to great lengths to secure the invitation because he had hoped the party would please her. However, Mathilde is disdained and irritated, and demands to know what he expects her to wear. She begins to cry and Loisel, gutted by her sadness, tries to comfort her. He asks her how much a new dress would cost, and after a moment of careful thought to avoid asking for too much, she replies that she would need 400 francs. Although he had put aside that exact sum of money to buy himself a gun so that he could go shooting with his friends, he gives Mathilde the money to buy a new dress.
The ball grows nearer and Mathilde purchases a new dress for the occasion. However, when the day arrives, she laments that she does not have any jewels to wear. Loisel suggests that she wear flowers as a replacement but Mathilde rejects the idea, mortified at the prospect of being perceived as poor. Loisel tells her to borrow jewels from her wealthy friend, Madame Forestier, and Mathilde rejoices at the idea. She hastily pays a visit to Madame Forestier, a classy and affluent woman. Madame Forestier graciously allows Mathilde to borrow whichever jewels she desires. After examining all of the jewelry that Madame Forestier has to offer, Mathilde selects an exquisite diamond necklace. She asks Madame Forestier if she can borrow the diamond necklace and Madame Forestier amicably agrees.