Episode 5 of "Mercy for None" kicks off with a haunting flashback, where Gi-seok watches the fleeing juvenile delinquents who assaulted him disappear into the night. Outside, Detective Han remains vigilant in his vehicle, unaware of the impending danger within. Inside, Gi-seok is unexpectedly set upon by a different masked assailant—a seasoned fighter, older and far more skilled than the kids he had just encountered. After an intense and grueling battle, the adversary delivers a fatal stab to Gi-seok's neck, abandoning him to his fate. Some time later, Detective Han steps into the parking lot, the grim discovery prompting him to report a homicide.
In the present timeline, Gi-jun's submerged car is miraculously retrieved from the depths, with Hae-beom discovering Gi-jun washed ashore and swiftly transporting him to safety in his own vehicle.
Elsewhere, Chairman Ju-woon and Chairman Bong-san converge, the air thick with tension. Bong-san confesses to orchestrating Gi-jun's murder to protect his son, then produces incriminating documents revealing that Detective Han was compensated by JW Gallery, a subsidiary of Juwoon Group. He levels accusations at Ju-woon, charging him with murdering Gi-seok, framing Jun-mo, and orchestrating a power grab to benefit his offspring. Bong-san declares that one of them must perish, setting the stage for a potential clash of titans. Soon after, Bong-san's henchmen are apprehended by prosecutors, much to the Deputy Chief Prosecutor's chagrin; Geum-son's team had beaten them to the punch by half an hour, allowing Bong-san to slip through the net.
Geum-son reveals his intention to target his own father next, following Bong-san's downfall. Meanwhile, Ju-woon confronts Yeong-do, waving the same incriminating documents Bong-san had shown him. He demands to know why Yeong-do ordered Detective Han to kill Gi-seok. Yeong-do protests his innocence, casting doubt on Geum-son as the true culprit behind Gi-seok's demise, thus deepening the web of intrigue and suspicion.
Meanwhile, Hae-beom escorts a still-fragile Gi-jun to the doctor's office. Hardly having regained his strength, Gi-jun insists on meeting Hae-beom, where he entrusts him with Gi-seok's suitcase and car keys. Back at NClean, Seong-won is spreading rumors of Gi-jun's demise when, to everyone's astonishment, Gi-jun himself appears. He urgently tasks Seong-won with uncovering his would-be assassin and is subsequently led to the columbarium, where the remains of Chun-seok and Byung-ho lie in silent tribute.
At Ju-woon's residence, tensions escalate as he confronts his son, Geum-son, who defiantly claims he was merely obeying orders. Meanwhile, Ju-woon's cronies relentlessly pursue Bongsan Group. Undaunted, Bong-san stands his ground, fighting alongside his loyal men. However, their efforts prove futile, and Ju-woon personally ends Bong-san's life. Amidst the turmoil, one Bongsan employee narrowly escapes harm, revealing himself as Yeong-do's clandestine informant. Through a phone call, Yeong-do congratulates the man, informing him that he is now set to lead Bongsan Group.
Inside Yeong-do's chamber, a grim list of struck-through names catches the eye—Bong-san, Jun-mo, and Gi-seok among them. Only Ju-woon's name remains unchecked. Determined, Yeong-do pays a visit to a imprisoned individual: the last man Gi-jun clashed with, an employee of Chairman Oh who knows the truth about Gi-jun's innocence in the Chairman's son's death. Now, however, this man is forever marked by his missing hand, a silent witness to his past ordeal.
Gi-jun subsequently encounters Ju-woon and inquires whether it was he who orchestrated the vehicular mishap. Ju-woon enlightens Gi-jun about Yeong-do, formerly known as Mr. Kim, a former policeman enticed by Chairman Oh to conceal their illicit deeds. Even subsequent to the chairman's demise, Yeong-do persisted in his collaboration, amassing substantial wealth. Yet, this proved insufficient to sate his greed, prompting him to resort to blackmail for additional funds. Ironically, it was Yeong-do's meddling that maintained a fragile truce between opposing factions. Ju-woon then produces an audio recording of a conversation between Yeong-do and Gi-seok, wherein Yeong-do reveals that Chairman Oh's son had set his sights on Gi-jun, prompting Gi-seok to eliminate him.
Ju-woon urges Gi-jun to assume control of his company, but Gi-jun politely declines, insisting solely on a confrontation with Yeong-do. Ju-woon assures him that he will facilitate the meeting.
At the precinct, Yeong-do receives a call from Ju-woon. The scene shifts to Yeong-do heading towards his vehicle, but his stride halts abruptly as he beholds something utterly astounding.
The epilogue of Mercy for None, Episode 5, unfolds with Yeong-do in conversation with the clandestine informant from Bong-san. Shortly thereafter, Seong-cheol and Geum-son join them, with the latter extending a handshake to Yeong-do, further entangling the web of intrigue and deceit.
