Episode 3 of "Mercy for None" kicks off with Chairman Bong-san commissioning an assassin to eliminate Gi-jun, but the assassin declines, acknowledging his inadequacy for the task. Subsequently, Bong-san orders his men to escort Jun-mo to a secure location, while also tasking one of his operatives with delving deeper into the circumstances surrounding Gi-seok's demise.
At the De’cro Hotel, Chun-seok urgently informs Jun-mo of their need to relocate to a safe house. However, Jun-mo grows impatient, failing to grasp the urgency surrounding a single individual. Just as Lee Dong-kyung, another loyalist of Chairman Bong-san, attempts to persuade Jun-mo to comply, Gi-jun makes a dramatic and violent entrance, causing a commotion. Chun-seok manages to whisk Jun-mo away to safety, while Dong-kyung engages in a fierce battle with Gi-jun.
Sim Seong-won is in the midst of preparing for his escape when Gi-jun makes an unexpected visit. Gi-jun grants Seong-won a single day to uncover Jun-mo's whereabouts.
Elsewhere, Seong-cheol ponders over Geum-son's enigmatic remarks and realizes that he must have been eavesdropping on his father. Seong-cheol searches the house meticulously and discovers Geum-son's sophisticated listening equipment. He confronts Geum-son, inquiring about his motive for revealing the spying. Geum-son subtly suggests a partnership, hinting that together, they could dismantle Bong-san's empire and seize control for themselves.
Inside the safe house, Jun-mo inquisitively questions Chun-seok about Gi-jun. Chun-seok's narrative transports us back to an eventful 11 years ago. During that time, Ju-woon and Bong-san served as second-in-command to Chairman Oh. They faced a losing battle against a formidable Busan gang, until Gi-jun arrived and turned the tables. This victory cemented Ju-woon and Bong-san's favor with the chairman, sparking rumors that Oh's company would ultimately be bestowed upon them, rather than upon Chairwoman Oh's son, Seung-won.
Seung-won's attempt to orchestrate the demise of Ju-woon and Bong-san did not sit right with the latter. In a fit of retaliation, Gi-jun ended Seung-won's life, thereafter counseling Ju-woon that Chairman Oh posed an imminent threat to their existence, urging them to strike first. While Ju-woon and Bong-san were undergoing interrogation at the chairman's residence, Gi-jun orchestrated a bloodbath, decimating Oh's entourage and effectively seizing control of the gang for them. Ironically, a moment later, one of Chairman Oh's loyalists confronted Gi-jun, revealing his awareness of Gi-jun's innocence in Seung-won's murder.
Subsequently, the newly appointed co-chairmen established a pact to uphold peace at all costs. However, since Gi-jun had ignited the conflict by eliminating Chairman Oh's son, he faced severe punishment—his Achilles tendon was sliced, and he was banished. Presently, Byung-ho paid Gi-jun a visit, cautioning him against confronting the Bongsan Group. Yet, Gi-jun remained unyielding. Meanwhile, Chairman Bong-san delved into the mystery surrounding Gi-seok's demise and discovered that Detective Han Seok-yun had overseen the investigation.
Back at the safe house, Jun-ho reached out to the foreign assassins from earlier and engaged their services to eliminate Gi-jun. Meanwhile, Gi-jun met with Chun-seok, who warned him against taking on the Bong-san clan. To everyone's surprise, Chun-seok provided Gi-jun with an address where he could find Jun-mo. Unbeknownst to Gi-jun, this was a setup. Jun-mo had persuaded Chun-seok that Gi-jun's demise would also save him.
The address led Gi-jun to a hotel undergoing renovation, where he was ambushed by the two foreign assassins. With remarkable prowess, he dispatched both assailants and subsequently used their phone to inform Jun-mo of their impending confrontation.
The epilogue of Mercy for None Episode 3 unveiled a shocking revelation: it was Gi-seok, not Gi-jun, who had slain Chairman Oh's son.
