Mi-rye Lee

Mi-Rye Lee is the main character of the 2015 South Korean thriller film Office. She works in the titular office, which has a darkened atmosphere after the police arrive looking for one of her coworkers, who is supposedly at large after he murdered his family.

Office (2015)
In the film's opening scene, Byung-gook Kim is seen arrive home from work one evening, and then murdering his family by bludgeoning them to death with a hammer.

The next morning, Mi-rye is seen hurrying to work, narrowly catching her bus. The police come to her office, looking for Mr. Kim and begin interrogating the employees. Mi-rye is instructed by her boss, Sang-gyu to say she knows nothing, however, Detective Jong-hoon manages to break her, and she confesses that Kim was not well liked by the other coworkers. Mi-rye is also disturbed to find Mr. Kim's knife in her desk drawer.

Mi-rye, is, for the first time since her interning for the office, allowed to participate in a staff meeting, which she excited by, as she believes it to be a sign she may be promoted to full-time, but she learns that Sang-gyu verbally abuses his staff during these meetings, and learns that the full-time employees are required to adhere to ridiculous performance standards. Meanwhile, detectives note that there is security footage of Mr. Kim entering his office building less than an hour after he killed his family, but there is no footage of him exiting the building, indicating he is likely still in the building.

Mi-rye hovers around her seniors, trying to make herself useful, but is never admitted into their inner circle. Mi-rye's circumstances are made worse by the arrival of Da-min, a new intern who’s more privileged and prepossessing, further endangers Mi-rae position. Their unspoken rivalry is very obvious to the other employees, and Mi-rae’s desperate fear of being replaced is partly validated by Da-min's clone-like resemblance in hairstyle and appearance.

That night, Jae-il stays behind in the office to work late, and is attacked by Mr. Kim. The next day, Jae-il is found hanging from the ceiling tiles with his throat slashed. Ms. Hong tells the detectives that she lied earlier about Mr. Kim's personality, and that she has seen him lurking around the office.

Ms. Hong later mouths off to Mi-rye, telling her that Da-min is better than her, and that she will likely take Mi-rye's position, causing the latter to go cry in the bathroom. Ha-young tells her that she is trying too hard, and it's painfully obvious that she's desperate. She advises her to take it a bit easier. That night Mi-rye is working late in the office and has a flashback to a conversation she had with Mr. Kim where he explains that caressing the knife (which was given to him by a man who committed suicide) helps calm him down, and, despite Mi-rye becoming visibly uncomfortable, he proceeds to demonstrate while telling her that he believes Mi-rye is a lot like him. Mi-rye tries caressing it herself, and believes it's working.

At the film's climax, Ms. Hong makes as scene in the office and leaves after she angrily quits after she tells Sang-gyu that she's tired of jumping through hoops for him, and that he didn't tell the police that he had fired Mr. Kim the same day that the latter murdered his family, just so the company wouldn't have bad publicity.

That night, when Sang-gyu is on his way to his car to head home, he is stalked on the stairway, and then attacked by an unseen figure. Ms. Hong, who was taking a taxi home receives a text message from Sang-gyu offering her a raise, so she reluctantly goes back to the office. She goes into the bathroom to freshen up, and is brutally knifed to death. Her assailant is revealed to have been Mi-rye who has apparently taken the persona of Mr. Kim, and gone on a homicidal rampage.

Ha-young and Won-sook return to the office and have a flirtatious exchange before they notice a manic Mi-rye making incoherent copies from her computer with papers all over the floor. The two become uncomfortable and prepare to leave, but Mi-rye flippantly asks them why they are leaving when they still have work to do, likely referencing their more-than-business relationship. Ha-young angrily slaps Mi-rye, and the latter bludgeons her with a hole-puncher before retrieving Mr. Kim's knife, which causes Won-sook to flea in panic, where he finds Sang-gyu murdered on the stairs.

Detective Jong-hoon returns to the building and prepares to enter, just as Mi-rye throws Ha-young out the window onto his car, causing him to realize that the killer is indeed in the building. Meanwhile, Jong-hoon's partner finds that Mr. Kim died in the elevator shaft some time ago after consuming cyanide, meaning that he couldn't have killed Jae-il.

Jong-hoon rushes to the office space, where he finds Mi-rye and Won-sook engaged in a struggle. Won-sook gains the upper hand when he stabs Mi-rye with the knife and begins strangling her, saying that she isn't Mi-rye, and that she's actually Mr. Kim. Jong-hoon fatally shoots Won-sook to get him to stop strangling Mi-rye.

In the film's closing scene, Jong-hoon is conversing with Mi-rye and she learns that public opinion is that all of the murders following Mr. Kim's death were committed by Won-sook, primarily because the police didn't have the funding to open a proper investigation, so they scapegoated Won-sook. When asked of the significance of the knife, Mi-rye says that it brings her peace.

Trivia

 * She is portrayed by award-winning former child actress Ah-sung Go.
 * It remains unclear why she murdered four people, although several possibilities exist:
 * Mr. Kim's spirit possessed her.
 * The knife was demonically possessed, and it was influencing both her and Mr. Kim.
 * She suffered a psychological breakdown after she realized she was going to be replaced.
 * There was foreshadowing that Mi-rye was going to become the new killer after Mr. Kim's death:
 * Mr. Kim stated that she is a lot like him.
 * Mr. Kim passed the knife on to Mi-rye before committing suicide, just as it had been passed on to him from someone who committed suicide.
 * When Mi-rye was crying in the bathroom, Ha-young stated that she's "exactly like Mr. Kim."
 * Mi-rye was sitting in the same spot at the cafe, looking down at her coffee as Mr. Kim did before he killed his family.