The Princess Bride starts out by describing the person who was the most beautiful woman in the world on the day Buttercup was born. We don't know who Buttercup is yet, but we can assume she's important. In any case, this other beautiful woman was named Annette, and her boss (a Duchess) became so jealous of her beauty that she constantly fed her chocolate to make her fat.
The book then walks us through all of the women who were most beautiful in the world as Buttercup grew up. Buttercup herself was always somewhere inside the top twenty, but according to the author, she never realized her potential because she didn't care about her appearance.
Meanwhile, there's this farmhand who works on her family farm named Westley. Buttercup's favorite thing to do is boss Westley around, but all the guy ever says in reply is, "'As you wish.'"
Buttercup finds out later on that her girl friends aren't paying much attention to her anymore because they're jealous—apparently every single boy in their town has a crush on Buttercup. Buttercup never pays any mind to the boys' advances, though; she's more interested in riding around on her horse.
One day, a man connected to the Florin royal palace finds out about Buttercup's beauty and mentions her to a man simply called The Count.
The Count then goes to tell the Prince of Florin, a guy named Humperdinck, about Buttercup's beauty, but not before going to Buttercup's farm to have a look for himself.
Buttercup's parents don't know what to think when the see the Count and his entourage entering their farm. Their first assumption is that they've done something wrong.
The Count (named Rugen) makes up an excuse for wanting to see Buttercup and pretends that he wants to hear more about the family's cows.
While the Count is admiring Buttercup, his wife (the Countess) is admiring Westley, who's walking around the farm with a bare chest. Buttercup can't help but pick up on the looks of attraction.
While lying in bed that night, Buttercup realizes that she's really jealous of the Countess. She has always assumed that Westley has belonged to her, which has made her take him for granted.
Buttercup runs to Westley's room in a passion and tells him she loves him… but he shuts the door in her face for her trouble. She's totally devastated, as you can imagine. How can a poor farm boy reject one of the most beautiful girls in all the land?
She later comforts herself by thinking that Westley is too stupid to say anything in response to her profession of love. And just like that, she feels her infatuation with him dying away.
The next evening, she hears footsteps and a knock at her door. Turns out that it's Westley. She makes sure to tell him that everything she said to him the night before was a total joke. Little does she know, though, that Westley has simply come to tell her goodbye—he plans on sailing for America to go make his fortune. But then he tells Buttercup that the reason he's going to make his fortune is because he wants to provide a good life for the two of them if they're going to get married. Because, you see, Westley is totally in love with Buttercup, too.
Before Westley leaves, he takes Buttercup in his arms and kisses her passionately.
After Westley leaves, Buttercup starts caring a lot about her appearance and becomes even more beautiful in the eyes of her town.
But then the unthinkable happens: Buttercup hears from her parents that Westley has been killed while his ship was being robbed by pirates off the coast of America. It turns out that the man who murdered him is called Dread Pirate Roberts, and has a reputation for never leaving any survivors.
Buttercup vows never to love again, and according to the author, she never does.