The Plot of the Story

To my mind, the author used the first paragraphs of the story to introduce the main character, Mathilde. Without naming her, he depicts the life-story of this woman. We get to know about her “background”, her social position and her unhappiness because of mediocre life.

“She was one of those pretty and charming girls born, as though fate had blundered over her, into a family of artisans. She had no marriage portion, no expectations, no means of getting known, understood, loved, and wedded by a man of wealth and distinction;….. She suffered endlessly, feeling herself born for every delicacy and luxury. She suffered from the poorness of her house, from its mean walls, worn chairs, and ugly curtains…… She imagined vast saloons hung with antique silks, exquisite pieces of furniture supporting priceless ornaments, and small, charming, perfumed rooms, created just for little parties of intimate friends, men who were famous and sought after, whose homage roused every other woman's envious longings…”

Exposition
    The action proper begins when Mathilde's husband, M. Loisel comes home with the invitation to the ball.  Mathilde now gets the best opportunity to appear in the the high society, she always wanted to belong to. But she has nothing to wear. This problem sets the rest of the plot in motion.

 “…"The Minister of Education and Madame Ramponneau request the pleasure of the company of Monsieur and Madame Loisel at the Ministry on the evening of Monday, January the 18th…" …She looked at him out of furious eyes, and said impatiently: "And what do you suppose I am to wear at such an affair?..”

The story itself.

 Her husband gives her all his savings  for a dress. But later she needs to have some jewels. She feels absolutely depressed. Fortunately, her friend Madame Forestier is able to provide her with a fabulous diamond necklace. Mathilde had a success. She was the most beautiful on the ball.

 

“Next day she went to see her friend and told her her trouble….

…She flung herself on her friend's breast, embraced her frenziedly, and went away with her treasure. The day of the party arrived. Madame Loisel was a success. She was the prettiest woman present, elegant, graceful, smiling, and quite above herself with happiness. All the men stared at her, inquired her name, and asked to be introduced to her. All the Under-Secretaries of State were eager to waltz with her. The Minister noticed her…”

The climax .

Perhaps, the most exciting and dramatic moment in the story is when Mathilde discovers that she has lost the diamond necklace (until that crazy twist in the last lines of the story). It's the turning point of the story. After having lost the necklace, Madame Loisel worked hard to buy the new one and to return it to the owner. Her life was very difficult. Their family spent 10 years to pay the debt.

  “…"What's the matter with you?" asked her husband, already half undressed.

     She turned towards him in the utmost distress.

     "I . . . I . . . I've no longer got Madame Forestier's necklace. . . ."

     He started with astonishment…”

"Madame Loisel looked old now. She had become like all the other strong, hard, coarse women of poor households. Her hair was badly done, her skirts were awry, her hands were red. She spoke in a shrill voice, and the water slopped all over the floor when she scrubbed it."

The denouement. 

Mathilde meets Madame Forestier on the Champs Elysées. The Loisels have finally finished paying off their debts for the necklace. All that remains is for Mathilde to see whether her friend ever noticed the substitution of the necklace. Mathilde wanted to tell her the sad story of the whole affair. But then unexpected turn of events.

“..I brought you another one just like it. And for the last ten years we have been paying for it. You realise it wasn't easy for us; we had no money. . . . Well, it's paid for at last, and I'm glad indeed...”

The anticlimax.

“"You say you bought a diamond necklace to replace mine?"

     "Yes. You hadn't noticed it? They were very much alike."…

     "Oh, my poor Mathilde! But mine was imitation. It was worth at the very most five hundred francs! . . . " “

The types of speech employed by the author of the analysed story is a mixture of narration and description with dialogues.