A girl named Lara Jean never openly confessed her love, but instead wrote a letter to each guy, revealing her feelings in it, sealed it and hid it in a box under the bed. But one day Lara Jean discovers that in some strange way all her letters from the secret box have been sent to their intended recipients. This unforeseen circumstance brings the girl face to face with all her former lovers: the boy who gave her her first kiss, the boy from summer camp, and even her sister's ex-boyfriend, Josh. As Lara copes with the surging difficulties, she realizes that something interesting and even very good can come out of this story with letters.