Episode 15 of "Good Boy" kicks off right back where we left off, in the bustling parking lot, with Jong-gu locked in a tense confrontation against Dong-ju. However, our heroic protagonist finds himself on the ropes, and it's not long before a powerful right hook sends him sprawling to the ground, unconscious.
Just as things seem to be spiraling out of control, Jong-hyeon bursts onto the scene, intent on coming to Dong-ju's aid. But Dong-ju, beside himself with rage and panic, reveals a shocking truth: he is completely blind. He implores Jong-hyeon to keep this secret from Han-na, at least for now.
The two men set off together, with Dong-ju trying to brush off his condition and refusing to seek medical attention. But Jong-hyeon, who understands all too well the plight of the punch-drunk fighter, insists on taking him to the hospital. With a blend of force and persuasion (strictly figurative, of course!), Jong-hyeon manages to convince Dong-ju to get checked out.
Meanwhile, on a higher floor, the Commissioner is whisked away in an ambulance after being shot. Someone needs to step up and interrogate him, and that task falls to Man-sik. This time, Man-sik stands his ground, but the crooked official proves to be a tough nut to crack.
Elsewhere, corruption rears its ugly head as Ju-yeong makes a daring escape from town, blackmailing the Insung Mayor into doing his bidding. He reminds the mayor that his only chance at survival lies in cooperating with Ju-yeong. Fail to do so, and his entire family will pay the ultimate price.
In Ju-yeong's absence, he communicates with one of his Russian gangsters, who is eager to move swiftly and secure the "Candy" for their upcoming deal. If things fall apart, the Japanese will not be pleased. This means Ju-yeong needs to retrieve the gear from Baek, and fast.
Ju-yeong swiftly tracks him down, leaving Baek frozen in his tracks like a deer caught in headlights upon beholding his boss. Realizing the game is up, Baek initially intends to divide the winnings fairly; however, his plan takes a dark turn as he instead orders his men to engage in a brutal contest of survival, decreeing that whoever emerges alive will claim their share. The warehouse is soon engulfed in a hail of gunfire.
The next morning, the team arrives at the warehouse, having been alerted to the gunfire by various reports. Jae-hong's concerns deepen as they somehow managed to bypass a minimum of seven checkpoints to reach the scene. Alas, this revelation suggests the presence of at least one more undercover police officer within their ranks.
Once more, the gang finds itself compelled to embark on a hunt for another police informer. Yet, they also come to realize that this saga runs deeper than mere money. Ju-yeong, already known for his unstable demeanor, seems to hold compromising information on individuals, compelling them into obedience. Each person on his payroll has amassed their fortune through overseas trade, including the chief prosecutor's father. Curiously, all these companies witnessed a sudden acceleration in their growth shortly after their association with Ju-yeong.
During his tenure at the Customs office, Ju-yeong began in the Intelligence Management Division, tasked with managing the integrated database. He transitioned paper records into the digital system, meticulously destroying the originals in the process. When Cheongil Shipping faced scrutiny over fax tax invoices, the investigation was sparked by a tip-off from within the customs office—a tip-off orchestrated by none other than Ju-yeong. Leveraging similar documents for other companies, he employed blackmail, used Leo to eliminate Oh Dollar, and dismantled other gangs before seizing control.
These documents hold far greater significance than the money itself, prompting Dong-ju to devise a meticulous trap for Ju-yeong. They intend to exploit an informant from the investigations unit and, unable to trust anyone—not even Dae-yong—they bug the radios and eavesdrop tirelessly.
This plan proved a resounding success, as they uncovered the identity of the mole, along with his disposable phone. It turned out that the same officer who had tipped Ju-yeong off at the construction site about the unfolding events was also the one accountable for Jong-hun's tragic demise. With the mole now apprehended, the gang set their sights on a jittery Ju-yeong, eventually tracking him down to a claustrophobic tunnel – not the same one where they had engaged in a massive brawl earlier in the season, but equally perilous nonetheless. In a daring maneuver, Ju-yeong managed to seize a car and flee the scene once more.
Having once again slipped through their fingers, Ju-yeong phoned the Mayor and instructed him to incinerate all incriminating documents. Han-na delved into her research and discovered that these documents were being stored at the Yeonsang-gu Public Library, a project that the Mayor had prioritized upon taking office. Without delay, the group rushed to the library and retrieved the evidence they sought.
Armed with this proof, they managed to corner the Mayor, who was attempting to make a hasty exit with a sack brimming with cash. However, their plans took an unexpected turn when he was wheeled out into the grand entrance hallway and compelled to face reporters. Deok-Gyu could only stand in despair at the unfolding chaos.
Meanwhile, Dong-ju's condition was worsening, and he was clearly struggling to keep it together. Jong-hyeon did his best to cover for him, but Han-na began to suspect that something was amiss. Her suspicions were further fueled when she received a call from her mother, informing her about some insurance documents.
But there was no time to dwell on this as the team received a lead on Oh Jong-gu's whereabouts. Dong-ju, determined and resourceful, was the one who tracked him down. With a steering wheel in his grasp – a result of Man-sik's ingenious idea to handcuff him to the car, which Dong-ju cleverly escaped – he engaged in a fierce battle with Mr. Oh.
This time around, Dong-ju emerges victorious, leaving Jong-gu unconscious on the ground and subsequently under arrest. Soon after, Han-na arrives on the scene, visibly shaken by Dong-ju's condition and the fact that she had not been informed. Meanwhile, Ju-yeong's sphere of influence continues to dwindle, prompting him to seek out the Japanese gangsters. He arrives bearing a truckload of Candy as a gesture of goodwill, but with a string attached – a favor in return. Driven by his desperate need to cover his tracks, part of which stems from his own destruction of the Candy-laden truck, Ju-yeong is determined to strike a deal.
Yeon-ha, aware of Ju-yeong's plan, decides to pass on a crucial tip, setting the group in motion to intercept the truck before it's too late. With adrenaline pumping, they manage to corner the vehicle, but their timely intervention is thwarted by a devastating explosion that erupts the moment they arrive, casting a shadow of despair over their efforts.
