The setting in the story is France. The two characters are Madame Loisel and Monsieur Loisel who are part of the middle class.
The necklace is gone!
The conflict is that Madame Loisel doesn't like her social class and wishes she was in a higher one.
Monsieur Loisel gets an invitation to a party but Madame Loisel doesn't want to go because she doesn't have a dress. Her husband gives her money to buy a new dress. Then she doesn't want to go because she doesn't have any jewelry. Her husband tells her to borrow a necklace from her friend so she chooses a diamond necklace from her friend.
That necklace was only worth 500 francs!
The Loisel's come home from the party and realize that the necklace Madame borrowed was missing.
Monsieur Loisel goes out to look for the necklace. When he doesn't find it, they get loans and money to buy a new 36,000 diamond necklace that looks similar to the necklace she borrowed.
Ten years later, after they finally paid off the debt from the replacement necklace, she runs into her friend that she borrowed the necklace from and told her that she lost the original necklace and bought a new one for 36,000 dollars. Her friend tells her the original necklace was only worth 500 francs.