After losing her beloved husband, thirty-year-old Holly Kennedy falls into despair, stops going out, and stops communicating with people. And then she receives a package of letters by mail: the letters can be opened only one per month, and they were written by the very person whose departure brought her such suffering.
It turns out that not long before his death, he decided to help her keep living. Each time she eagerly waits for the first day of the month to open the next envelope—and, following the instructions strictly, take another step that pulls her back to life: buy a new dress, take part in a karaoke competition, go to the sea.