Miss Night and Day revolves around a woman in her twenties, who spends half of her day as herself and the other half as a fifty-year-old. All episodes are now streaming on Netflix.
Warning: This article contains heavy spoilers
Plot summary
Lee Mi-jin has been working hard to become a civil servant for the past eight years. Although she passes the civil service exam, she fails the interview round every year.
This year is no different, except that due to the selection of a girl with the same name, Mi-jin’s parents mistakenly believe that she has finally become a civil servant.
Mi-jin does not reveal the truth to her parents, which makes her feel guilty. Constantly faced with failure, she decides to give up on preparing for the civil service exam.
That night, she jumps into a well to save a stray cat. In that moment, Mi-jin wishes to be someone else other than herself. Miraculously, her wish comes true.
She wakes up as a fifty-year-old woman the next morning and only returns to her own body after the sun sets. The pattern repeats itself every day.
Mi-jin turns her curse of being a fifty-year-old woman during the day into an opportunity by assuming her aunt’s identity and applying for a senior citizens’ internship at the District Prosecutors’ Office.
As Senior Public Intern Lim Sun, Mi-jin impresses everyone by saving the life of a celebrity, Ko Won, who is assigned to public service after a scandal.
Mi-jin’s daytime persona, Lim Sun, is then promoted to the position of office aide to a prosecutor named Gye Ji-ung, who is known for being efficient but hard to work with.
Ji-ung had previously rescued Mi-jin from a scammer and had accidentally left some of his documents with her, so Ji-ung and Mi-jin meet again, and Mi-jin ends up encountering the killer Ji-ung is after.
Around twenty years ago, there were cases of women suddenly disappearing in Seohan, including Ji-ung’s mother.
It turns out that this killer is responsible for those disappearances as well. The killer now targets Mi-jin, whom Ji-ung promises to protect.
Mi-jin works with Ji-ung as Lim Sun during the day and meets him as Mi-jin at night. Over time, the two develop feelings for each other and start dating.
However, Ji-ung still does not know about Mi-jin’s curse. The only people who do know are Ga-young, Mi-jin’s best friend, and Ko Won, who also has feelings for Mi-jin.
With their help, Mi-jin tries to find the cat that triggered the curse, hoping to break it to have a normal life, but all her attempts fail.
Meanwhile, Ji-ung makes progress in the murder cases and starts suspecting Baek Cheol-gyu, a senior public intern like Lim Sun.
Baek, a respected and charitable man, has given up the management of Hwadong Medical Center, but he is still the hospital’s director in name.
Ji-ung, Lim Sun, and Byung-duk, an investigator working under Ji-ung, find evidence linking the illegal distribution of fentanyl to the hospital.
When Lim Sun and Byung-duk go to search the hospital, Baek kidnaps Lim Sun and reveals that his wife was one of the women who went missing twenty years ago.
Baek had approached Mi-jin’s aunt, whose identity Mi-jin is now using, for help in finding his wife. Soon after, Mi-jin’s aunt quit her job and left the city.
Baek’s wife’s body was then discovered in a motel room, leading him to suspect Mi-jin’s aunt. He has been looking for Lim Sun since then to discover the truth about his wife’s murder.
As the sun goes down, Lim Sun turns into Mi-jin. She is rescued by Ji-ung, and Baek is arrested. The kidnapping makes Mi-jin suspect that her aunt never left; she went missing like the other women.
Mi-jin reveals the truth about her curse to Baek and convinces him to help her find the killer. With Baek’s help, Ji-ung’s team gets a new suspect: a woman named Gong Eun-sim.
Ending explained:
Who is Gong Eun-sim?
Mi-jin learns from Ko Won that the District Prosecutors’ Office has been receiving anonymous tips about a senior public intern faking their identity.
Believing the tip is about herself, Mi-jin investigates, only to discover that the tip is about a fellow intern, Na Ok-hui, who supposedly got the job by stealing someone else’s identity.
Mi-jin asks Byung-duk to run a background check on Na Ok-hui. She also quits her job as Lim Sun when Ji-ung comes to know that his office aide has also been lying about her identity.
The background check on Na Ok-hui reveals that the woman claiming to be Na Ok-hui is actually Gong Eun-sim, Ji-ung’s suspect.
After Na Ok-hui was selected as a senior public intern, Gong Eun-sim killed her and stole her identity to get the job. She also killed Ko Na-heun, who witnessed the murder.
Mi-jin realizes that the killer she encountered weeks ago was Gong Eun-sim when she finds poppy flowers in Gong Eun-sim’s locker, the same scent she had smelled on the killer.
Mi-jin informs Ji-ung about Gong Eun-sim being the killer. Despite knowing how dangerous Gong Eun-sim is, Mi-jin is forced to confront her alone when Gong Eun-sim kidnaps her father.
The killer’s arrest
When Mi-jin goes to rescue her father, Gong Eun-sim takes her captive. Gong Eun-sim has been targeting Mi-jin for a while and finally has the chance to kill her.
Mi-jin now knows that Gong Eun-sim killed Baek’s wife for money. She killed Mi-jin’s aunt because she suspected her, and Ji-ung’s mother because she witnessed the murder.
Ji-ung finds out that Mi-jin has been kidnapped by Gong Eun-sim and reaches Gong Eun-sim’s old house, where Mi-jin is being held captive.
Mi-jin manages to free herself and overpower Gong Eun-sim. By the time Ji-ung finds Mi-jin, the sun is starting to rise, resulting in Ji-ung witnessing her transform into Lim Sun.
Gong Eun-sim is arrested. The police search her house and find the bodies of Mi-jin’s aunt and Ji-ung’s mother buried in her backyard, finally giving their families closure.
New beginnings
Mi-jin makes the difficult decision of breaking up with Ji-ung, who is being transferred to Seoul, as she does not want to burden him with her curse, which seems unbreakable.
Although her future remains uncertain because of the curse, she starts preparing for the civil service exam once again.
The longer she stays in her fifty-year-old body, the more she starts valuing her youth. Due to her failures, she used to despise being young.
Now that she has lost her youth, she realizes its value. The moment she acknowledges that her youth was a gift, she breaks the curse.
Her fifty-year-old self says goodbye to her and makes her see her own strength. Breaking the curse allows Mi-jin to testify against Gong Eun-sim during the day.
Gong Eun-sim is sentenced to death, while Baek receives a lenient sentence of three years. On the other hand, Lim Sun becomes a legend among the senior interns who come next.
Mi-jin’s experiences as Lim Sun give her the confidence to successfully pass the civil service exam and interview. She goes on to become an investigator.
The lives of Ko Won, Byung-duk, and Ga-young also change. Ko Won releases a solo album inspired by his love for Mi-jin, and Ga-young starts dating Byung-duk.
Mi-jin is assigned to work under a prosecutor in Seoul. There, she meets Ji-ung again. They both realize that they still have feelings for each other and get back together.
Mi-jin, who was once a failure, gets everything she ever wanted, thanks to the curse, which she now sees as a gift, and her own hard work.