The story follows Kate, a sorter at the Dead Letter processing center, who unexpectedly discovers a mysterious letter addressed to the "deceased" Charles. Following the map, she uncovers an old tin box letter that has been sealed for 32 years and discovers that the recipient is a real estate fraudster who has been on the run for years by faking death. After setting up a trap to bring him to justice, she took the lead in establishing the "Dead Letter Search Project", searching for clues from undeliverable dead letters and finding many people who had been erased by the system and forced to lose contact. Eventually, she helped Angela, who had been missing for forty years, reunite with her brother, interpreting the warm core of "Letters don't die, people shouldn't be erased".
