Mathilde Loisel is an attractive woman who is married to a clerk in the Ministry of Education. She is dissatisfied with her humble life and longs for a life of luxery. When her husband returns one day with an invitation to a ball hosted by his work, he believes that she will be very happy at the prospect of attending such an event. However, Mathilde is extremely upset and explains through her tears that she has no beautiful gown to wear to such an occasion and says that it is cruel for him to offer her such an invitation.
Her husband hates to see her so upset and gives her money for a new gown. As the party approaches, Mathilde reveals that she is upset because they cannot afford to buy new jewels. Her husband suggests that she borrow something from her wealthy friend, Madame Forestier. Mathilde borrows a beautiful diamond necklace from her friend and is the belle of the ball. At the end of the night she discovers that she has lost the necklace.
The Loisels search for a replacement for the necklace and find one that is worth 40,000 francs. Monsieur Loisel buys the necklace and Mathilde gives it to Madame Forestier in place of the original necklace. The Loisels spend 10 years working extremely hard to pay back their financial debt (as a result of purchasing the necklace). Monsieur Loisel takes three jobs and Mathilde spends all her days doing arduous housework. They live in crippling poverty until all their debt is cleared.
One day when she is out on a walk, Mathilde sees Madame Forestier. Madame Forestier does not recognize her as the beautiful woman she was once was. Mathilde responds bitterly that the change in appearance was due to all the hardships she endured to replace her necklace. Madame Forestier exclaims that the diamond necklace was a fake and not worth anything.