Returning to April 2005, we finally see the events of Kyung-tae’s death. Kyung-tae spills fuel in the midst of trying to light a stove in his yard, and while his friend Gyu-min is in the outhouse, Jong-soo and his cronies show up to beat the living daylights out of Kyung-tae. When Gyu-min next peeks outside, the yard has caught on fire. In the aftermath, a call from Sang-eui sends Jun seo rushing to Kyung-tae’s house, but by then it’s already too late — everyone has made it out, except for Kyung-tae.
With that, we return to the present day. While Yoon-ho is out, Jae-kyung pays his house a visit, where an on-site investigation reveals Yoon-ho used his wife’s car to commit the Molotov cocktail arson at Myung-guk’s house. Yoon-ho’s wife capitalizes on Jae-kyung’s brief distraction to call Yoon-ho and warn him of the police’s pursuit. He immediately goes into hiding, emerging only to threaten Tae-jin into helping him evade the authorities, though Tae jin seems impatient with him.
Meanwhile, Cha-hyun updates the rest of the shady trio on Jae-kyung’s suspicions, then asks them why they followed Jun seo’s instructions so compliantly that fateful night. We aren’t told of Jong-soo’s reasons, but it seems Jun seo knew of Tae Jin’s affair with Ji-yeon.
As for Chi-yeon, he has a solid motive. He and Yoon-ho bashed Myung-guk to death and sealed his corpse in the freezer storage, because Myung-guk had been threatening to expose Jong-soo’s drug addiction. Jun seo coerced Chi-yeon into showing up at the construction site by threatening to call the police to the freezer storage, necessitating that Chi-yeon and Yoon-ho retrieve the body.
Elsewhere, Jae-kyung realizes that’s why Yoon-ho murdered the store owner, because he’d passed by that CCTV on his way to retrieve the body with Chi-yeon. One thing’s amiss though; Chi-hyun has no idea who then moved Myung-guk’s rotten corpse to his home, but it must have taken at least two people to lug him around.
As for our trio, it’s Yoon-jin’s birthday today, except Joo-song’s surprise cake winds up waiting forlornly on the balcony while Jae-kyung and Yoon-jin pore over Myung-guk’s research journals. To their credit, they make good progress, realizing that Myung-guk had been meeting with Sang-eui regularly in Pilo-dong — but they’re then interrupted by an unwelcome visitor.
It’s Ji-yeon, who asks that they investigate a pension that Jun seo opened over a decade ago, then brazenly demands her right to his inheritance. Yoon-jin bristles at her lack of shame, and that’s the exact moment Joo-song bursts out of the balcony with Yoon-jin’s cake. Cue the most awkward birthday celebration ever, lol. Unexpectedly, the occasion shocks Ji-yeon to the point she throws up in the bathroom, and Yoon-jin ultimately connects the dots. Jun seo’s passcode has always been Yoon-jin’s birthday.
The next day, Yoon-jin seeks out Joo-song for some advice. Having overheard her phone call with her colleague while hiding out on the balcony, Joo-song’s already figured out what she wants to ask. She wants to keep the large sum in Jun seo’s locked account for herself. Yoon-jin staunchly defends her intentions — it’s better than having the money go to hypocrites like Tae-jin and Ji-yeon. Still, Joo-song knows it’s all for herself, even as she denies it.
Unfortunately, a friend’s dissuasion can’t outweigh a mother’s desperation to provide for her child. Yoon-jin calls Tae-jin to a PC cafe that she booked, luring him in with the claim that she knows Jun seo’s passcode and threatening to circulate the photos of him and Ji-yeon, in exchange for half of Jun seo’s money. With no other choice, Tae-jin allows Yoon-jin to enter the passcode — only for it to turn out wrong. Infuriated, Tae-jin strangles Yoon-jin, until Joo-song rushes in. Yanking Tae-jin off her, Joo-song hurls him aside, then carries the unconscious Yoon-jin out.
Circling back to our cops, their current mission is tracking down the drug dealer Jin-wook. Ms Yoon has captured her underling, since they failed to hold up their end of the deal, and she informs Chang-soo that he can drop by and arrest them both in half an hour. Except when Jin-wook arrives, he fatally shoots Ms Yoon with the gun he’d previously stolen from Jae-kyung.
At that very moment, Jae-kyung has been following the hearing aid thug all the way to the same building. He bumps into Chang-soo just as a gunshot rings out, and when they rush into Ms Yoon’s hideout, Jae-kyung recognizes her back room as the place he’d been drugged in.
On the way to the station, the hearing aid thug demands that Chang-soo set him free, threatening to reveal his acceptance of Ms Yoon’s bribes and Jae-kyung’s addiction. Caught between a rock and a hard place, Chang-soo impulsively decides to drive his car right off the road and into a river, diving out of the window at the last second. Chang-soo survives, while the thug dies, but Jae-kyung realizes the window has been rolled down — this wouldn’t have been possible underwater, which means that Chang-soo intentionally plunged the vehicle.
This is happening just when Jae-kyung and Chang-soo were starting to solidify a rapport! He’s acting suspicious even though he may have a good reason for what he’s doing.
Meanwhile, Tae-jin, was humiliatingly put in his place by CHAIRMAN WON despite Tae-jin’s outstanding aptitude and fervent drive to lead the Pilo-dong project, Chairman Won reiterates that he’s only useful as a prosecutor, so he shouldn’t greedily aim any higher. Needless to say, the ambitious Tae-jin has already set his sights on greener pastures and vaster horizons, and is already ahead of all his opponents.