Episode 17 of "Seoul Busters" kicks off with the image of two male students ambling their way home. One student vents about the daunting nature of their recent exams, while his companion casually remarks that he guessed on a few questions and aced them all. Envy gnaws at the first student, and when his friend dashes off to chase a ball, he impulsively shoves him towards an approaching truck, resulting in a harrowing collision.
Elsewhere, Hyun-woo keeps a vigilant watch on Jun-ho, who is surreptitiously trailing a young woman. As Hyun-woo's phone rings, Jun-ho seizes the moment to slip away unnoticed.
Meanwhile, the team gathers for dinner on a dreary, rainy evening at their beloved haunt. Yu-bin receives a call and excuses himself to attend to it. Tan-sik spots a wallet lying abandoned on the floor and picks it up, only to be startled by a snapshot of Yu-bin with his girlfriend. This discovery sparks a conversation about Yu-bin, prompting Min-seo to reveal that she had heard whispers about him almost tying the knot in America.
Our seasoned storyteller, Jong-ryeok, indulges in a imaginative spree, wondering why Yu-bin abandoned his promising career in America to return to Korea. He speculates that Yu-bin might have fallen for a female serial killer who shattered his heart by refusing to reform her ways—a twist inspired by Yu-bin's once-uttered belief that even criminals can fall in love.
Jung-hwan balks at this fantastical tale and spins his own yarn. He insists that he overheard whispers about Yu-bin stealing Hyun-woo's girlfriend, reasoning that Yu-bin fled the country in disgrace for betraying his friend's love. However, this theory crumbles under scrutiny, as Hyun-woo and Yu-bin remain steadfast friends.
As for Tan-sik, his mind drifts back to a time when Yu-bin casually mentioned being shot in the arm. He ponders a chilling possibility: perhaps the mafia assassinated Yu-bin's girlfriend on their wedding day as grim retribution for his probing into their illicit activities.
He conjures up a scenario where Yu-bin, fueled by a vengeful spirit akin to Vincenzo's, launched an assault on the gang, securing his own justice. In the depths of his imagination, he even envisions Yu-bin's demise, earning rebukes from his colleagues. One might ponder, why bother with detective work when they could thrive as imaginative writers? Amidst their theoretical discussions, Yu-bin surprisingly reappears, revealing his injury to be the result of a toy gun, much to their disappointment.
The following dawn, the team is dispatched to Songnae Mountain, where a woman's lifeless body lies discovered. The disadvantages, however, stack up: a lack of CCTV surveillance in the vicinity and the perpetrator's theft of the victim's possessions. Yet, after a closer inspection, Yu-bin posits that the woman was likely slain elsewhere and her body merely dumped in the forest-clad mountain as an afterthought. He further deduces her to be an art major, judging by the splashes of paint adorning her sleeves and fingertips . Moreover, he believes the killer intentionally staged the discovery, hoping the body would be found. Min-seo nods in agreement, aligning with his insights.
Simultaneously, Tan-sik apprised them of a strategic placement of the body, astutely positioned between two borders, casting a shroud of uncertainty over jurisdiction. Jung-hwan, true to his erratic nature, flip-flopped again, this time ingratiating himself to Yu-bin. As the investigation delved deeper, they uncovered the victim's identity: Jung Hyun-joo, an art student at a nearby university. Yu-bin's hunch had been spot on. Despite Hyun-joo's humble familial background, she resided in a lavish city apartment. Jong-ryeok and Tan-sik ventured to the university, intent on interviewing Hyun-joo's peers.
En route, they munched on gimbap, with Tan-sik commenting on the spinach's peculiar scent. Jong-ryeok's stomach, unfortunately, betrayed him mid-conversation with the students, grumbling loudly and forcing him into an embarrassment of flatulence. Seeking refuge, he embarked on a lengthy trek to find a men's toilet, an arduous task given their location at an all-female institution. Along his journey, he serendipitously encountered a cross-dresser acting perversely. Determined, Jong-ryeok chose to apprehend the perpetrator before attending to his discomfort.
In the meantime, Jung-hwan and Min-seo arrived at Hyun-joo's abode, discovering her cat cowering in a closet and a card pointing to a bar where Hyun-joo had once worked. Parallel to this, Yu-bin revisited the crime scene, piecing together clues with meticulous scrutiny. He deduced that the perpetrator was a muscular individual aged between 20 and 35, tall, predominantly left-handed but adeptly trained in using his right hand as well.
He popped into Eun-kyung's office, where he learned that Hyun-joo had been asphyxiated using ketamine, a substance not easily accessible to the public. The telltale marks on Hyun-joo's face suggested that the assailant had employed their left hand to cover her face with cloth. Eun-kyung's astute observation of a left thumb impression, despite the culprit being right-handed, added another layer of complexity to the puzzle.
Meanwhile, Hyun-woo engages in a thorough discussion of the case with his students, noting its eerie resemblance to another he had encountered in America. This particular incident evokes haunting memories for Yu-bin, stirring recollections of his girlfriend's tragic fate.
Their story began in Korea, when fate intervention led them to miss the final bus on separate occasions – Yu-bin after a concert, and Ja-ein after a seminar. By chance, Ja-ein propositioned sharing a taxi back to Seoul, and their casual encounter set the stage for what was destined to be. A year later, in America, their paths crossed again, gradually blossoming into a profound love. Together, they shared immeasurable joy, eventually moving in with each other.
However, their happiness was abruptly shattered on the day Ja-ein was brutally murdered. They had planned to attend a concert, but Yu-bin's seminar was rescheduled, forcing him to cancel their outing. Despite his heartache, he offered to meet her as soon as his obligations permitted. Alas, a grim call about her demise rushed him back home, where he found Hyun-woo immersed in the investigation. They barricaded him from entering the crime scene, but from the threshold, Yu-bin's shattered eyes caught a glimpse of her lifeless body, covered reverently in a pristine white sheet.
Sometime later, another detective handed him the necklace Ja-ein clung to in her dying moments. Yu-bin had gifted her the bracelet, its emblem sparking playful conversations about its hidden meaning. After poring over the case files, the significance of the symbol dawned upon him – it represented friendship. Ja-ein's final act was an attempt to convey that her killer was someone she considered a friend. During that chaotic time, suspicion incorrectly fell upon Han Jun-ho, prompting Yu-bin to follow him back to Korea in pursuit of justice.
