To All the Boys I've Loved Before is a 2014 novel by Korean-American author Jenny Han. The protagonist and narrator is Lara Jean Song-Covey, a half-Korean, half-Caucasian teenager, who is the middle child of three girls. The majority of the novel takes place after Lara Jean’s older sister Margot goes to school abroad in Scotland. The daughters live with their father, as their mother died several years ago from a head injury.

The introverted Lara Jean keeps a bundle of letters to former crushes in a hatbox. The box was given to her by her mother, who passed away when she was nine. Lara Jean writes theses letters to her various crushes over the years—with no intention of sending them—as a way to process her emotions and remember the power of her feelings. The recipients of the letters include, primarily, Josh: her sister Margot's ex-boyfriend (with whom she broke up to go to Scotland). Josh and Lara Jean are friends and neighbors, and Lara Jean has always had feelings for him. Other recipients of the letters includes Peter Kavinsky, who Lara Jean kissed in seventh grade; John from model U.N.; Kenny from summer camp; and Lucas from homecoming. One day, Peter approaches her at school and says that he does not have feelings for her. At this point, Lara Jean realizes with horror that her love letters (many of which were written long ago) have somehow been delivered to the intended recipients. She hastily explains that the letter was written a long time ago.

Peter has just broken up with Genevieve, Lara Jean’s former friend and current foe. When Josh approaches Lara Jean in school about the letter he’s also received, she lies and tells him she is seeing someone. Josh asks who it is she’s dating, and Lara Jean blurts out that it is Peter—he has just walked down the hallway and is in her line of sight. She spontaneously kisses Peter and he reciprocates. The two agree to create a ploy: they will pretend to be together so that Genevieve knows Peter has moved on, and Josh knows Lara Jean is over him.

Lara Jean and Peter lay out a set of ground rules for their fake relationship. One of the rules is that Peter will write Lara Jean notes, and the two will attend the school ski trip together. They spend more and more time together and both begin to separately develop feelings for one another. Josh gets jealous of Peter’s closeness with Lara Jean. When she confronts him about his behavior, he kisses her. She realizes she doesn’t want Josh at all but instead has begun falling for Peter. 

On the big ski trip with the school, Lara Jean and Peter become closer than ever. The two end up kissing in a hot tub and Peter tells Lara Jean he wants to date her in actuality. The next day, Genevieve tells Lara Jean that there is a rumor Lara Jean and Peter had sex in the hot tub, and Peter did not publicly deny it. Lara Jean is crestfallen and keeps her distance from Peter during Christmas. 

At the annual party hosted by the Song-Coveys, Kitty invites Peter, who then tries to make amends with Lara Jean. Josh steps in to defend Lara Jean, and Margot (who is back from school on break) finds out that Josh kissed Lara Jean. This leads to a spiral of confusion and tension. 

By the end of the novel, Lara Jean learns that Kitty (her younger sister) has sent the letters to their recipients, including Peter, to prevent Lara Jean from revealing Kitty’s crush on Josh. All three sisters reconcile. Lara Jean also discovers that she does indeed have feelings for Peter, reinforced by the little notes that Peter wrote Lara Jean during the span of their “fake” relationship. She confesses her feelings to him at the novel's close and he reciprocates.