Episode 5 of "Seoul Busters" kicks off with an ominous revelation from one of Hyo-joo's closest friends, painting a chilling picture of her ex-boyfriend, Jung-hyun, a relentless stalker. They shared academic halls but their breakup only fueled his obsession, prompting Hyo-joo to seek solace in a temporary hiatus. Yet, Jung-hyun's shadow lingered, and her friend's conviction lingers—he was haunting them that fateful evening.
Meanwhile, Yu-bin revisits the crime scene, his mind a whirlwind of fragmented clues. Despite meticulous contemplation, a nagging sensation persists that he's overlooking a crucial piece. He replays the events in his mind's eye, yet certain aspects remain elusive, defying comprehension.
The investigative team convenes for a briefing, their suspects under the microscope. Jung-hyun looms large on the suspect list, with Joong-ryeok's gut instinct pointing straight at him. Next in line is Sang-ju, the neighboring chicken restaurant owner embroiled in a feud with Mr. Yoon and suspected of arson in three separate incidents. The landlord, with a potential windfall from insurance claims, also comes under scrutiny. Lastly, Mr. Yoon himself enters the fray.
During the briefing, Jung-hyun's attention strays, captivated by a T-Rex figurine lying on the floor. In a comical turn, Tan-sik's playful nudge sends him sprawling, inadvertently losing the toy. Yu-bin promptly directs the team to arrange interviews with these suspects, inviting Mi-seo to accompany him on a visit to Mr. Yoon's abode.
At Mr. Yoon's residence, a heartbreaking revelation unfolds—Hyo-joo's mother, a victim of depression, lies bedridden. Mr. Yoon expresses disbelief that the fire could be deemed arson, swiftly shifting the conversation to Hyo-joo's recovery, his hope for her full restoration shining through. As they depart, Mi-seo's heart goes out to Mr. Yoon, but Yu-bin remains stoic, adhering to his principle of trusting only what he can see, his judgment of Mr. Yoon's character suspended in ambiguity.
Later, Yu-bin finds solace in the Forensic office, offering Eun-hyung a soothing cup of tea. Her findings are sobering—a flammable liquid ignited the blaze, suggesting premeditation. The question lingers: was Hyo-joo's assailant also the arsonist? Eun-hyung's uncertainty only deepens the mystery surrounding this case.At the bustling office, Joong-ryeok delves into the recording of Hyo-joo's frantic call to the police, her fear of her obsessed ex-boyfriend palpable in every strained syllable. Suddenly, his phone rings, disrupting his concentration. It's Tae-sung, urgently informing him that Mr. Yoon has been summoned for questioning.
Without hesitation, Joong-ryeok reaches out to an old contact, weaving through his network to track down Jung-hyun. Upon locating the spoiled young man, Joong-ryeok moves in to make the arrest, only to be met with a fierce resistance from Jung-hyun and his equally entitled friends. The confrontation escalates into a physical altercation, forcing Joong-ryeok to use necessary force to subdue them. Finally, Jung-hyun is taken into custody and brought to the precinct.
Upon arrival, Joong-ryeok discovers Tan-sik's blunder—he inadvertently summoned all suspects to the station simultaneously, creating a logistical nightmare. The team is left with no choice but to divide and conquer the chaos. Min-seo tackles the landlord, uncovering his unusual habit of purchasing excessive insurance policies, fueled by an unrequited crush on the charming insurance agent. Meanwhile, Tan-sik interviews Sang-ju, peeling back layers to reveal the man's aversion to fire, stemming from a past trauma that left him scarred.
Joong-ryeok and Jung-hwan corner Jung-hyun, who's already summoned his lawyer, ready to fight. Jung-hyun threatens to press charges against Joong-ryeok for excessive force, his temper flaring when Hyo-joo's name is mentioned. He grudgingly admits to tailing her that night but claims to have lost her and spent the remainder of the evening gambling with friends.
Just as Yu-bin prepares to confront Mr. Yoon, news arrives that Hyo-joo has regained consciousness. The detectives rush to the hospital, only to find that her traumatic brain injury has robbed her of her memories. The doctor's prognosis hangs heavy: there's no guarantee when, or if, Hyo-joo's memories will return, dashing the detectives' hopes of swiftly resolving the case.
As Jung-hwan trudges home after a grueling day, his daughters remind him of his promise to bring them a T-Rex figurine. He vows to fulfill their wish and engages in a heartwarming conversation with his entrepreneurial wife, who's busy knitting and launching a YouTube channel.
The following morning, Jung dedicates his entire morning to a fruitless search for the elusive T-Rex figurine within the hospital's confines. The mood at the precinct turns sour when the police chief storms in, scolding the team following a call from higher authorities. It transpires that Jung-hyun's father is not only wealthy but also wields considerable influence. The threat of punishment looms large, but Mi-seo stands her ground, fiercely defending Joong-ryeok.
A mere few moments after the team's arrival, they reconvene for yet another briefing, the air buzzing with anticipation. Tan-sik unveils a captivating video from a popular YouTuber, who, with a sheepish confession, reveals that his accolades for the city's finest chicken eateries were nothing but a paid promotion. Yu-bin, unfazed, had already harbored doubts about Mr. Yoon's culinary prowess. Meanwhile, Joong-ryeok's loyalty to his former mentor remains steadfast, refusing to entertain the notion of deceitful marketing tactics.
As the meeting disbands, Jung-hwan's path crosses with Dong-goo, the little boy clutching a T-Rex figurine like a treasure trove. A playful tug-of-war ensues, but Dong-goo's grip remains steadfast.
Elsewhere, Yu-bin retraces his steps to the crime scene, his mind whirling with unanswered questions. Returning to the office, he's briefed on the team's meticulous investigation, which has left all suspects but Mr. Yoon in the clear. Yu-bin posits that Mr. Yoon's foreknowledge of the impending blaze explains his hasty exit, clutching his beloved boxing medal, and his subsequent nonchalance towards the detectives' inquiries. Joong-ryeok, fiercely defensive, finds himself at odds with Yu-bin's factual assertions, seeking solace in the outdoors where a chance encounter with children's sandcastles offers a fleeting distraction and a chance to rebuild.
Summoned by Tan-sik's triumphant call, the team gathers once more, only to be met with a technological mishap. Tan-sik's elaborate video presentation, meant to showcase his groundbreaking find, is marred by a corrupted file. Undaunted, he reveals a intriguing connection between a food delivery app and several local restaurants, igniting new leads. Yu-bin dispatches Min-seo to delve deeper into the insurance angle, while assigning Jung and Tan-sik to revisit the neighbors. Yet, he makes a compassionate decision to shield Joong-ryeok from further involvement, fearing it might weigh heavily on him.
Through the neighbors' testimonies, a distressing picture emerges of Mr. Yoon's dire financial straits, his multiple business failures leaving him buried under a mountain of debt. The insurance agent sheds light on an unexpected turn of events, revealing that Mr. Yoon had suddenly settled three months of overdue premiums mere months prior. However, the agent dismisses arson for insurance fraud as a motive, arguing that the payout would barely scratch the surface of his overwhelming loans.
The episode draws to a cliffhanger as Joong-ryeok ponders his next move, his phone buzzing with a cryptic message. An anonymous tipster claims to hold the key to unraveling the mystery of the fire, leaving the detective both intrigued and uncertain of what lies ahead.
