Madam Loisel resents her middle class life that she was born/married into, and constantly daydreams about having a wealthy life
Madam's husband gets her an invitation to a grand party in hopes of helping her rich fantasy but it makes her very upset as she has no dress
With some savings, Madam buys a dress, but is upset with its blandness, and goes to a friend to borrow something. She picks out a beautiful diamond necklace to borrow for the ball.
At the ball, she is the center of attention; dancing with every man and finally living her fantasy.
Madam loses the necklace on the way home, and cannot find it. They scrape together every penny and loan to buy it again. Madam and her husband become depressed, working and working to get the money back.
After 10 years, Madam is no longer is debt from buying back the borrowed necklace she lost. She runs into the friend in which she returned the necklace to, tells her the story, and is shocked when the friend tells her that the original necklace was a cheap fake.