Episode 1 of *To The Moon* opens with a mesmerizing visual of a magical train, soaring through the cosmos toward the moon. The scene swiftly transitions to Jung Da-hae, a spirited young woman, sitting in an interview for a full-time position at Marron Confectionary, where she has recently completed an internship. Just as she is nearing the end of her internship, a mischievous bee delivers a sting, causing her to tumble off her chair and lose consciousness.
In a dreamlike sequence, Da-hae encounters a vision of her future self, who solemnly warns her against accepting the job, predicting it will lead to a life of unhappiness. However, Da-hae, driven by necessity, remains resolute in her need for employment. Awakening with a swollen eye, she bravely completes her interview.
Fast forward to 2017, and we find Da-hae and her manager, Ko Dae-young, scrambling to make it to a crucial meeting. Their tardiness is a result of Ko's insistence on grabbing a coffee, which he then carelessly spills all over Da-hae. To make matters worse, he forces her to sprint up 14 flights of stairs to arrive just in time.
Upon their arrival, Manager Ko instructs Da-hae to deliver some cakes to the executives. Ascending in the elevator, she finds herself in an unfamiliar room, adorned with books, games, and a plush massage chair. Mistaking it for an employee lounge, she decides to indulge in a moment of relaxation. But fate has other plans; the power plug slips out, trapping Da-hae in the chair. Just then, the door creaks open, revealing Ham Ji-woo, the rightful owner of the office. With a mix of embarrassment and urgency, he helps her out of the chair. Flustered, Da-hae quickly hands him the cakes and flees the scene.
Soon after, Da-hae discovers that the employee evaluations have been released. We are then introduced to Kang Eun-sang, a member of the sales team, and Kim Ji-song, who works in accounting. All three women—Da-hae, Eun-sang, and Ji-song—have received average ratings in their evaluations.
A brief flashback reveals how these three women forged a bond. As off-cycle hires without degrees from prestigious universities, they found themselves on the fringes, ostracized by their peers. It was in this isolation that they discovered solace in each other's company, forming an unbreakable friendship.
At present, the trio is out for a meal, airing their grievances and sharing evaluations. Ji-song regales her friends with tales of her Chinese boyfriend, Wei Lin. Da-hae, meanwhile, is preoccupied with worries about her boyfriend, Lee Byeong-jun, who has vanished without a trace since the previous night. She keeps her concerns to herself, not divulging a word to her friends. Eun-sang attempts to share news of her new cryptocurrency investments, but Ji-song cuts her off mid-sentence, rushing back to the office in a hurry.
After work, Da-hae's attempts to contact Byeong-jun prove futile. Concerned, she heads to the police station to report him missing. She recounts to the policewoman how she and Byeong-jun were about to have dinner the night before when she proposed the idea of moving in together. Suddenly, Byeong-jun noticed the absence of a corkscrew to open their wine bottle. He left to buy one but never came back.
Unable to locate him or get a response to her calls, Da-hae describes the situation to the policewoman. As she speaks, a realization dawns on her—Byeong-jun hasn't disappeared; he's left her. Withdrawing her report, she departs from the station.
That night, as midnight strikes, marking Da-hae's birthday, she is taken aback to find Byeong-jun standing outside her door. He admits he was too ashamed to face her, professing his love but claiming that their financial circumstances make marriage and starting a family impossible. Da-hae laments having fallen for him and walks away, her heart heavy. Ji-song and Eun-sang, who had been waiting to surprise Da-hae for her birthday, overhear the entire exchange.
Da-hae wanders the town, recognizing this as the future version of herself she had once envisioned. Ji-song and Eun-sang catch up to her, offering solace. To compound her misery, Ji-song reveals she overheard Byeong-jun on the phone—he's been cheating on Da-hae. The trio tracks Byeong-jun down, finding him in his car with his other girlfriend. In a fit of rage, Da-hae dumps a bucket of eels over him. Right behind him, in another car, sits Ham Ji-woo, looking on with a bemused expression.
As the girls make their way back, they cut a cake for Da-hae. However, their laughter quickly fades as both Da-hae and Ji-song lament playing a losing game. Yet, Eun-sang remains optimistic, telling them they still have a chance to achieve everything they desire. She suggests they dive into the world of cryptocurrency.
An epilogue reveals Ham Ji-woo at Da-hae's interview. He inquires about her dreams, to which she responds that she yearns for a normal, average life. She describes it as one where she can receive immediate treatment for a bee sting instead of enduring the pain during a job interview, knowing full well she'll forfeit the opportunity if she leaves midway.
