Episode 1 begins with Jae-Won running for her life and being followed by a man in a mask and all-black clothes. As he catches her and chokes her to death, we’re taken back in time to when things were fantastic for Jae-Won. Jae-Won designs furniture and is now the CEO of her own company called Derêve. We’re taken back to three days before the murder attempt to see how CEO Jae-Won functions. She’s quite a meticulous worker, hence the successful business, and she loves to be part of the actual design work. She’s even employed a dear friend from college to do a paint job for her as a fellow artist. Yoon-Jin claims to be overjoyed by the fact that her friend is taking such good care of her, but something seems fishy there.
Jae-Won is so busy at work that she can’t even make it home every day. Even on her father’s birthday, it’s her assistant sending in gifts and cake while she’s engrossed in work and doesn’t remember until she’s on a video call with her daughter and husband. At work, she has a designer named Te-O working for her. They’re working on what looks like a nanny cam-like device—a home camera with an aesthetic design. Te-O tells Jae-Won that the launch date for the product needs to be pushed back. She takes some convincing but ends up agreeing, staying back at work, while he heads out on a date (disgusting!). Out of the blue, when she’s all alone at work, the lights go off, and a man dressed all in black starts to chase her around with a hammer. She tries to escape and hides in a room, but he breaks the glass door after multiple attempts at breaking the handle and makes it inside. She tries to call the police, open a chat through the office laptop, and use the landline, but to no avail. Fortunately, just as he’s about to get to her, the security guard shows up, possibly because all the lights went out. The man dressed in black escapes, and Jae-Won is left shivering in fear. Earlier that day, she had received some flowers from her stalker, and while speaking to the police, she reveals she’s been stalked for about 7 years now (yikes!), but never physically.
The police learned that the CCTV was under maintenance on the day, so all employees were essentially suspects. Jae-Won calls Te-O to handle an interview the next day because she’s all shaken up; however, in front of him, she pretends to be just fine. As if this incident started a domino effect, Jae-Won was met with an insurance policy worker the next day. According to Tae-Joo, the insurance guy, Jae-Won’s mother had set up a policy for herself a little before she died. After she died, her father had silently pocketed the amount, something Jae-Won hadn’t even heard of until the present day. Jae-Won defends her father, but it’s revealed that he is actually her stepfather. Tae-Joo also says that her mother was taken into the emergency room three times before she died from drinking pesticide “accidentally.” This is rather suspicious, which is why Tae-Joo is investigating the case now. Jae-Won dismisses the idea, but as the day progresses, she thinks about it further and even tells her husband about it. However, she doesn’t tell him about the stalker (hmm). Jae-Won doesn’t have the best relationship with her daughter, especially in comparison to her husband. She’s quite stiff around her because she doesn’t get to spend much time with her.
Back at work, Jae-Won finds a parking slip near her desk and realizes it could belong to the stalker. She told her assistant to stop the investigation and not release any press articles because it would taint the brand’s image. She then uses the slip and finds the t-shirt the stalker was wearing hidden in the boot of the car. It happens to be Te-O’s car, and she’s devastated to realize her close friend and confidant might be the one trying to kill her. She tries to reach her husband to talk to him, but he’s nowhere to be found. She goes to the gym he’s meant to be at and learns he hasn’t been a member for three months. She gets her employee to track his smart watch and is stumped when she finds out that her husband is cheating on her with Yoon-Jin (ugh).
Jae-Won feels the weight of everything that’s going on and leaves in the middle of a shoot to get some air. Te-O follows her out, but she’s afraid of him and takes a few steps back when he tries to talk to her. She walks the other way and gets caught in the rain, crying her eyes out because of everything that she’s learned in the last 24 hours. As much as she wants to get help, she can’t taint her public image or her company’s image. Like a palindrome, we’re taken back to the beginning of the first episode of My Happy Ending, where Jae-Won was running from someone near the Han River. She runs into the danger zone, and before you know it, the man’s caught up to her and is choking her on the bridge. He tosses her off it, and somehow, the police are made aware. We can assume the officer she tried to speak to before realizing who she was could’ve realized something was seriously wrong. Ultimately, at the end of episode 1 of My Happy Ending, Jae-Won wakes up in the hospital surrounded by the three men who have betrayed her (men = trash). At that moment, she decides that she will put them through the same hell that they’ve put her through.