Episode 7 of "Gangnam B-Side" unfolds with Prosecutor Min boldly asserting her desire for a more prominent role in Choi's schemes, yet behind closed doors, she leaves Mrs. Ryu an enigmatic message that hints at deeper machinations.
At a bustling intersection, Gil-ho springs into action, swiftly rescuing Dong-woo from imminent danger while K taunts him relentlessly. A haunting flashback reveals a teenage Gil-ho, driven by revenge, brutally beating K and leaving him scarred for life. In the present, the arrival of the police provides K with an opportunity to release his captives, and he promptly informs Choi, who issues a cold-blooded order: eliminate Gil-ho and Dong-woo.
Desperation grips Dong-woo as he pleads with Gil-ho for assistance, confessing that Ye-seo seeks to avenge Jae-hee's demise. Gil-ho, however, merely observes that Dong-woo has finally grasped the depths of his own emotions and deserts him. Left with no other alternatives, Dong-woo reaches out to Su-in, who puts on a indifferent face despite her secret involvement in aiding the girls. Troubled by Dong-woo's plight, she pretends indifference but her heart is heavy.
His efforts lead him nowhere, prompting Dong-woo to seek information from Min-hee, the injured escort. To his astonishment, she reveals a crucial detail: she recently encountered K at the now-shuttered HYENA club, where a stash of Neon was being dealt.
Elsewhere, Su-in confronts Ye-seo, urging her to return home to her father. But Ye-seo, armed with Jae-hee's incriminating video, refuses to budge. She insists on taking action, urging Su-in to join her in their fight. Motivated by Ye-seo's resolve, Su-in hides her when K arrives to check on the girls.
Concurrently, Dong-woo, having arrived at HYENA with the same intention as Gil-ho, persuades him to forge an alliance. Their common goal: to destroy K and Choi. Suddenly, Psyche attacks, but Gil-ho neutralizes him with ease. The drug dealer then reveals a cache of Neon that K has stored at the abandoned club for an upcoming launch, sparking an idea in the duo's minds.
Psyche calls K, falsely claiming that Gil-ho and Dong-woo are stealing the drugs. Yet, thanks to a cleverly hidden camera at the club, K sees through the ruse and realizes it's a trap.
We come to understand that Jae-hee, prior to her association with Madam Baek, was employed by Su-in, who once aided her in evading the clutches of the formidable K. Su-in's compassion extends further, as she once again steps in to assist Ye-seo, who cleverly conceals a crucial video within a plush toy gifted by Dong-woo, her vape concealing a blade as a hidden danger. Ye-seo entrusts the plush to Su-in, who promptly informs Dong-woo of their whereabouts, urging him to come to the rescue of the escorts. Tragically, K eavesdrops on this conversation and metes out severe punishment to Su-in. He also identifies Ye-seo and alerts Choi to her presence.
Dong-woo hesitates, torn between duty and fear, but Gil-ho urges him to act swiftly and save Ye-seo. Seeking revenge, Gil-ho attempts to confront K, but is subdued by the latter's thugs who administer a tranquilizer. Meanwhile, Dong-woo arrives at the scene to find it deserted, K having abducted everyone. Amid the ruins, he discovers Su-in's lifeless body, the plush toy still clutched in her hand. With heavy heart, he plays the video recorded by Jae-hee, which uncovers a clandestine meeting between Choi's inner circle, their escorts, and other key figures including Jae-hee, Jung-hwa, Choi, Prosecutor Tak, Mayor Woo, and several influential assemblymen. The meeting introduces Neon, a substance tested on an unwilling escort, revealing its sinister potential.
Furthermore, Dong-woo receives a clue leading him to a mysterious location where he encounters Mrs. Ryu. It transpires that following Joon-seo's demise, Min has been orchestrating a long-term strategy to bring Choi down, now poised to deliver the decisive blow. Dong-woo rushes to Hae-il Tech, pleading with Min to hold her action until he can secure his daughter's safety.
As Gangnam B-Side Episode 7 concludes, Min arrives at the headquarters and confronts Choi's inner circle, including Prosecutor Tak. The gathering is a calculated test by Choi to ascertain Min's loyalty. Tak, poised to ascend to the Minister of Justice, taunts Min for her audacious attempt to apprehend him. The climactic revelation of the meeting is another unethical experiment—administering the latest batch of Neon on selected girls, Ye-seo among them, pushing the boundaries of morality and humanity to their limits.
