Episode 8 unfolds with Bin's heartfelt letter to Tang, where he extends his apologies and urges Tang to forge ahead independently, trusting in his instincts, assuring him that his inner strength will be his ultimate savior. Tang, after much contemplation, makes a decision rooted in his own resolve and chooses to return to aid Bin.
Nan-gam arrives at the hospital, confronting the harsh reality of his father's demise while finding solace in his mother's well-being. Distraught, he dashes out of the hospital and leaps into his car, where Roh Bin awaits, ready for their next move. The other officers, realizing Nan-gam's intent to confront Chon, are powerless to stop him before he speeds off. Bin attempts to enlighten Nan-gam, asserting that Tang is exceptional, having taken lives for a just cause, mirroring Nan-gam's current pursuit of Chon.
Elsewhere, Tang, stealing a vehicle in haste, tracks Bin's real-time location. Bin arrives at the designated rendezvous point to find Chon already present, having anticipated their arrival. Chon, sharp as a tack, detects Nan-gam's concealed presence nearby. Nan-gam draws his weapon, aiming it at Chon, but Tang's sudden appearance complicates the standoff. Chon, amusement etched on his face, declares that the situation is turning thrilling. With a swift pull of the trigger, Chon initiates a fiery gun battle.
In the chaos of bullets flying, Roh Bin is hit, and Tang, in a desperate bid to save him, falls short. As Bin lies wounded, he queries Chon's motive for showing up at all. Chon responds, asserting that the world requires individuals like them to uphold justice. He reveals that he had been monitoring Tang's criminal exploits, pondering if one could truly distinguish the virtuous from the wicked. When Nan-gam pleads for Chon to cease, Chon turns his wrath onto him, dropping a bombshell revelation: Nan-gam had mistakenly believed his mother had an affair with Chon, but in truth, it was with his father's other subordinate – Nan-gam's former captain.
Does Song Chon manage to escape his fate? A nostalgic glimpse reveals a youthful Chon, eagerly distributing energy drinks to a squad of officers combing through the woods. Detective Jang Gap-su, Nan-gam's father, reprimands him for meddling in affairs of a different precinct. Despite repeated attempts, Chon's endeavors to impress Gap-su consistently fall flat.
One day, as a cafeteria worker prepares to return to her hometown, Jang entrusts her with a package destined for someone in China. To everyone's shock, it contains drugs, unraveling the truth that Gap-su had been illegally peddling confiscated narcotics for half a decade. The unsuspecting woman is apprehended and, overwhelmed by despair, takes her own life. Enraged, Chon confronts Gap-su, but his courage only earns him a brutal beating. Gap-su retaliates by branding Chon as the offspring of murderers, sparking a fierce altercation that culminates in Chon taking Gap-su's life.
As Nan-gam absorbs this grim tale, his demeanor darkens, and Tang's neck tingles with unease. Offering to terminate Chon himself, Tang senses Nan-gam's resolve. Just then, Chon, having extracted the blade embedded in his side, lunges at Tang, but Nan-gam intervenes swiftly, fatally shooting Chon.
In a separate act of compassion, Nan-gam rescues Rex from euthanasia. His father's funeral solemnly unfolds, followed by a visit to Yong-jae in the hospital, where signs of recovery are evident.
Back at the precinct, Chon and Roh Bin are scapegoated for the spree of murders. A flashback unveils Roh Bin confessing to Nan-gam his intention to bear the burden alone, driven by a steadfast belief in upholding justice. Roh Bin even underwent dental modifications to match Tang's bite, the sole evidence tying Tang to the Professor's murder in Busan, left behind on a piece of fruit.
Nan-gam consults with the seasoned profiler from earlier seasons, who theorizes that Roh Bin's transformation stems from the profound emotional trauma he endured after his parents' demise. She then turns the conversation towards Tang, leaving Nan-gam to ponder his next steps.
A haunting flashback transports us to the grim location where Bin and Chon met their fate. Nan-gam confronts Lee Tang, querying the reason behind his return. Tang replies, stating that if he hadn't come back, the chaos he unleashed would continue indefinitely. He then places a solemn request to Nan-gam, begging him to end his life. Weary of constant evasion, Tang pulls the trigger, but to his astonishment, the gun fires only a blank. Nan-gam, unmoved, grants Tang his freedom with a dismissive gesture and departs. Soon, an electric spark ignites the premises, transforming it into an inferno. Despite Tang's desperate attempts to rescue Roh Bin, he is helplessly overcome by the flames. Casting a final, poignant glance at his fallen friend, Tang relinquishes hope and flees.
Tang's mother arrives home to find the snow meticulously cleared from their front doorstep. Her husband claims ignorance, prompting her to venture outside to seek the mysterious snow-shoveler. However, Tang has already vanished, having retreated to the tranquil shores. Chung-jin, accompanied by his family, catches sight of Tang's solitary figure but remains silent, observing from afar.
The narrative of "A Killer Paradox" concludes in an unexpected twist. Tang seemingly emigrates to a warmer climate, embracing a modest, diligent existence to scrape by. Yet, fate intervenes as he is apprehended for being an undocumented immigrant. Intriguingly, he discovers that his criminal record is spotless, devoid of any prior offenses, leaving him bewildered.
A flashback illuminates a pivotal moment, revealing a profiler inquiring Nan-gam about Tang's involvement in the case. Though Nan-gam's response is inaudible, the subsequent visuals clarify that Tang has been officially cleared of suspicion. Tang, empowered by this revelation, returns to Korea. One fateful day, Nan-gam strolls with Rex when whispers of a remarkable reversal surface: a murder victim was himself suspected of abduction and murder.
As Tang meanders through the bustling streets, an unexpected collision startles him. A chilling sensation creeps up his neck, prompting him to turn around, leaving the narrative hanging on a cliffhanger, filled with mystery and anticipation.
