Episode 4 of *To The Moon* kicks off with a dreamy sequence where Da-hae boards a fantastical crypto train soaring towards the moon. Her ethereal journey is abruptly interrupted by the arrival of her mother at her new apartment. Over a breakfast table laden with warmth and familiarity, Da-hae sets up a new YouTube account for her tech-challenged mother, a gesture filled with love and modernity.
Later, Eun-sang, a pragmatic friend, calls Da-hae, urging her to take on a weekend side job to boost her finances. Eun-sang herself supplements her income by working as a designated driver. However, Da-hae's resolve wavers as she finds herself at a karaoke bar, savoring a cold beer instead of heeding Eun-sang's advice.
Monday morning dawns with the three friends converging on the bus, bound for work. The bus TV flickers to life, broadcasting news of a motel fire that occurred over the weekend. The report features an interview with a woman whose face is obscured, but it's unmistakably Da-hae. In a flurry of panic, she dashes off the bus before her friends can utter a word.
At work, Da-hae's boss drops a bombshell: the anonymous account Hoppang Bite has shared her interview on the company's message board, amplifying her embarrassment. During a tense lunch with her friends, Da-hae clams up when questioned about her motel companion. Her phone rings, displaying a contact named Huge Mistake, adding an air of mystery. Her friends, amused, tease her about her penchant for men with prominent veins.
The viral nature of her interview spirals out of control, with vicious comments flooding the internet. Her friends valiantly defend her online, while Da-hae discovers that even her mother has joined the fray, fiercely protecting her daughter's honor in the comment section. Overwhelmed, Da-hae calls her mother, insisting she can handle the backlash alone.
Just then, Ham Ji-woo appears, having overheard snippets of Da-hae's conversation. He sports a bandage on his arm and reveals his attempts to reach her, but Da-hae remains elusive. Is Ji-woo the enigmatic Huge Mistake? The question lingers as Da-hae is jolted by a fleeting memory from the motel night: herself, scribbling something on a man's arm.
Back at the office, Eun-sang takes matters into her own hands, posting a complaint on the news station's forum about the poorly blurred video of Da-hae. A journalist from the channel contacts her, promising to remove the videos. This journalist turns out to be Kim So-young, a reporter familiar with Eun-sang from a previous incident involving her daughter, Ji Sang. The conversation veers towards a daycare bus accident, hinting at the possible cause of Ji Sang's demise, though confirmation remains elusive.
In the bustling accounting department, a lively debate erupted over the blurred visage of an actress in a viral photo that had everyone talking. Ji-song, with a keen eye for detail, correctly identified the actress by spotting her distinctive ring. However, her triumph quickly turned sour when she noticed that Soo-jin was sporting an identical, exorbitantly priced ring, sparking a twinge of jealousy. Later, Ji-song sought solace and vented her frustrations to Wei Lin, only to find her words lost in translation due to a language barrier. Sensing the tension, Oh Dong-gyu, who was fluent in Chinese, stepped in and offered to bridge the communication gap with his translation skills.
Meanwhile, Da-hae and Da-hee found themselves in a meeting with a store manager for work-related matters. The manager, ever the observant, commented on the supposed romance between Da-hee and Ji-woo, musing how well-suited they would be as a couple. Da-hee was quick to clarify that they were not dating, but the conversation seemed to rub Da-hae the wrong way, leaving her visibly annoyed.
Later on, Ji-song, still carrying the weight of her earlier jealousy, dragged Eun-sang to a jewelry shop. There, she poured her heart out, recounting how her home had once been a haven for clutter and trash, driving her to seek out beauty and elegance in everything she owned. She revealed a tumultuous past, where her mother had abandoned her for a cult and her father had left to pursue a monastic life. The two friends ended up drowning their sorrows in drinks at a nearby pub, the night stretching on endlessly.
In a separate twist of fate, Da-hae found herself bombarded with a flurry of texts from an unknown sender dubbed "Huge Mistake." To her surprise, the mystery texter turned out to be none other than Ji-woo, the very person she had shared a memorable night with in a motel. In his message, Ji-woo proposed a meeting to clear the air. Suddenly, memories flooded back to Da-hae—she recalled being captivated by the veins on his arm, so much so that she had playfully written "National Treasure No 1" on it with a marker. Realizing the marker might still be visible, she panicked and rushed to intercept Ji-woo before he could uncover the incriminating evidence beneath his bandages.
Da-hae arrived at Ji-woo's opulent apartment in a towering, fancy building, her heart pounding with anticipation. She scrambled to check his arm, but alas, Ji-woo had already caught a glimpse of her handiwork and couldn't resist teasing her about her creative expression of affection.
A flashback whisks us back to the previous night. Ji-woo, brimming with excitement, plays a newly composed song for Ju-man, his musician buddy. Yet, Ju-man’s reaction is far from enthusiastic; he dismisses it as subpar and advises Ji-woo to keep music as a mere pastime. After a disheartening phone call with his mother, Ji-woo seeks solace in a karaoke bar. There, amidst the dim lights and echoing melodies, he catches the familiar strains of his own song emanating from a neighboring room. Curiosity piqued, he steps over to find Da-hae, the source of the rendition, lost in the music.
They soon find themselves lost in a haze of alcohol, with Da-hae recounting a tale of her youth. At 18, with her family on the brink of financial ruin, she was thrust onto a TV show. Ji-woo, coincidentally, had also performed his song on that very show, albeit with crippling stage fright that left him floundering. Da-hae, finding solace in their shared embarrassment, had since clung to that song as a lifeline through her darkest moments. This revelation fills Ji-woo with an indescribable joy, and as the night wears on, their connection deepens, culminating in a tender kiss. The evening ends with them retreating to a motel, where passion takes its natural course.
Fast forward to the present, Ji-woo confronts Da-hae, accusing her of evading him. Da-hae, with a hint of bitterness, points out the stark contrast in their circumstances—he, a member of the privileged, she, a striver from the have-nots. She proposes they dismiss their night together as a fleeting mistake and move on. But Ji-woo counters, highlighting that Da-hae, with her mother's unwavering support, is in a better position than he, who had rashly destroyed his apartment in a bid to pursue music full-time.
Later, Da-hae confides in her friends, revealing her ambitions to be unapologetically greedy and seize everything she desires. She shares her foray into the world of cryptocurrency, where she's poured her savings in hopes of a brighter future. With determination gleaming in her eyes, she declares her intent to chase a better life, one where Ji-woo remains within her grasp.
An epilogue transports us to 2004, where a young Ji-woo stands on a TV stage, his voice trembling as he sings his own composition. He falters, the audience erupts in laughter, but unbeknownst to him, this moment spares Da-hae from further ridicule at school, her own appearance on the show now a distant, forgotten memory.
