Episode 8 of "Gangnam B-Side" kicks off with the girls undergoing a rigorous security check at headquarters. K mocks Ye-seo mercilessly but ultimately allows her to sneak in her vape, unbeknownst to him that it harbors a concealed blade. Meanwhile, thugs escort Gil-ho to the headquarters, but the tranquilizer's effects wane, enabling him to overpower his captors and slip away. As he dials Dong-woo, both are astounded to discover their unexpected convergence at the same locale. In a daring maneuver, Gil-ho rams a van into the entrance, creating a diversion for Dong-woo, who anxiously searches for Ye-seo.
Inside, the inner circle convenes for a pivotal meeting. Prosecutor Min Seo-jin presents the contract outlining the drugs' launch plan. Choi Hak-gu then unveils his dual-edged scheme: Leon, the drug, and Leon Plus, its purported antidote. The girls chosen by Su-in and K are unwitting pawns in an illicit clinical trial. The doctors administer Leon to the first girl, who suffers an immediate attack, followed by Leon Plus as the cure. She momentarily recovers but then convulses and passes away. The room falls into a stunned silence, yet Choi dismisses it as a necessary evil and pushes for Ye-seo to be next. However, Min intervenes, redirecting the focus to the contract signing. Tak, incensed by the unequal profit distribution favoring Choi, voices his discontent.
How do Dong-woo and Gil-ho intervene to thwart Choi's plans? Dong-woo, barely escaping K and his henchmen, seizes the moment to expose the incriminating video to the inner circle, stunning them into silence. Tak seizes control, tearing up the contract and demanding Choi to rectify the situation, alongside an equitable share for all. But Choi's cold calculation prevails; he shoots Tak, appoints Min as his replacement, and coerces the remaining inner circle members to sign the revised contract before making a swift exit.
Outside, Dong-woo's plight intensifies, but Gil-ho arrives like a knight in shining armor, engaging the thugs while urging the former cop to focus on finding Ye-seo. Gil-ho's confrontation with K reaches a fever pitch, their long-simmering animosity boiling over. Despite a fierce battle, Gil-ho is eventually subdued, with K slicing his Achilles tendon and stabbing him in the shoulder. Yet, Gil-ho's survival instincts ignite; he seizes the knife, plunges it into K's eye, and shoves him down the stairs, leaving both men battered but defiant.
Inside, Ye-seo stands alone amidst the fallen girls, her survival a stark contrast to their stillness. Choi summons her forward, initiating a false camaraderie. She introduces herself as Jenny, but her alias falls flat against his knowing gaze; he taunts her about Jae-hee, sparking a fierce anger in Ye-seo. With a stab intended for retribution, she lunges at him, yet he deflects her effort with ease. Seizing Leon as leverage, Choi summons Dong-woo, who finally locates them. Dong-woo's plea for mercy falls on deaf ears as Choi administers the deadly drug to Ye-seo, triggering a violent seizure. In a panic, Min scrambles to administer the antidote, and Ye-seo's life miraculously returns to her. Yet, amidst the turmoil, Choi slips away unnoticed.
Dong-woo chases after him, bullets ricocheting off Choi's fleeing vehicle, which collides with Gil-ho's van. Grabbing Choi, Dong-woo's rage fuels a brutal beating, leaving Choi inches from death's door. Gun aimed, Choi mocks Dong-woo anew, but Ye-seo's arrival halts the assault. Just then, Gil-ho steps in, seizing the weapon and executing Choi with a point-blank shot to the head. As he limps away, memories of Jae-hee flood his mind.
In the aftermath, Dong-woo and Ye-seo mend their bond, finding solace in each other's presence. Time passes, and they visit Jung-hwa and Jae-hee's graves, Ye-seo's heart heavy with nostalgia for the joy she shared with Jae-hee. Jae-hee's video surfaces, exposing the inner circle, leading to their arrest. Hae-il Tech faces scrutiny, and the launch of Leon and Leon Plus is postponed indefinitely.
In an interview, Min confesses her complicity, driven initially by ambition but turning against corruption when she realized its depths. She vows to cooperate and bear the consequences of her weakness.
The final scene of Gangnam B-Side Episode 8 reveals Dong-woo reinstated as a policeman. A club blaze illuminates his path to a burning pile of drugs, Neon among them. Recognizing Gil-ho's handiwork, Dong-woo chases him out, the pimp limping away. Their eyes meet, and a shared smile passes between them before they part ways, each carrying their own secrets and destinies into the night.
