Episode 3 of "Mad Concrete Dreams" commences with a flashback to five years prior. Su-jong, Hwal-seong, and their respective spouses, Kim-sun and Yi-gyeong, are on a holiday vacation. As they swim in the ocean, Hwal-seong plays a prank on his wife by pulling her underwater. He then poses a hypothetical question to Su-jong: if his wife were drowning, would he save her? Su-jong confidently assures him of his willingness to do so. However, when the same question is posed to Hwal-seong, he jokes that he wouldn't, as his wife is too valuable.
In the present timeline, Su-jong is fleeing from a kidnapping scene while the police give chase. He manages to evade them, but his car runs out of gas shortly thereafter. A kind passerby offers to help him get gas since he's stranded in the rain. Once the Good Samaritan leaves, Su-jong abandons the vehicle and runs off on foot with the suitcase containing the money, leaving the car's trunk open. When the Good Samaritan returns, he discovers Yi-gyeong and calls the police.
While the police arrive at the abandoned car and rescue Yi-gyeong, Su-jong drags the suitcase through the rain back to the Seyun building. He deletes the CCTV footage of himself leaving with a heavy bag and returning with the suitcase. He counts the money and packs it into delivery bags, while storing the rest in a backpack to pay off his debt at Real Capital and clear his conscience.
As he stacks the money with a sense of relief, guilt haunts him at night as Hwal-seong appears in his nightmares accompanied by the police.
The next morning, Kim-sun receives a call from Ju-ran using Yi-gyeong's phone from the hospital. She calls Su-jong and asks him to show up at the hospital first thing in the morning. Although Su-jong would prefer to visit in the afternoon, Kim-sun, who is aware of his involvement in the kidnapping, insists that he prioritize the hospital since his best friend is in a coma and his wife was kidnapped. Nonetheless, Su-jong still chooses to head to Real Capital to pay off his loan. However, Yo-na refuses to process it, claiming that office hours start at 10 am. When Su-jong confronts her about Kim-gyun's death, they remain unfazed. He loses his cool and goes after Yo-na, but Dr. Jang stops him.
Su-jong is left with no choice but to make his way to the hospital, carrying a backpack brimming with cash. Surrounded by the police, he's thrown into a fluster, but Kim-sun steps in to offer her silent yet steadfast support. Earlier, when she went to retrieve a change of clothes for Yi-gyeong, she discreetly deleted incriminating messages from their chats using Hwal-seong's laptop.
Su-jong then returns to Real Capital and pays off the debts, acquiring sole ownership of the Seyun Building. Meanwhile, Morgan Lee calls Yo-na to inquire about the progress of acquiring the Seyun building. She watches as Su-jong makes the payment and secures his loan contract, updating him that something has come up but that she'll handle it.
He spends time with his family, telling Da-rae that they should travel to the United States for surgery to get hearing aids. Da-rae is overwhelmed by the news, while Kim-sun looks at Su-jong with a complex expression.
While everything seems to be going smoothly for Su-jong after the events, Ju-ran has her eye on him after seeing him in Hwal-seong's pictures, and his name comes up during the investigation of Chang-su. Even though Yong-hoon shoots down her suspicions, she still pursues the lead.
When the man Su-jong encountered that night is questioned again as a witness, she shows him a photo of Su-jong. The witness can't remember since Su-jong was wearing a mask, but he feels a sense of familiarity towards him. Ju-ran brings Su-jong to the police station for questioning, putting the witness behind a glass screen for identification. Her interrogation is interrupted by Yong-hoon, who is furious that she's gone against his directives.
Just then, Kim-sun arrives at the police station with Yi-gyeong. She provides a false alibi, claiming that Su-jong arrived home around midnight. This further casts doubt on the witness, who ultimately fails to recognize him as the man he encountered.
After leaving the police station, Kim-sun and Su-jong stop by a restaurant for food. Kim-sun finally asks the question she's been holding back on since the day of the kidnapping. Su-jong responds with a look that confirms her suspicions. She asks him to explain everything once they finish eating.
At the end of the episode, Su-jong is already asleep at home. Kim-sun receives a call from Yo-na asking if everything is progressing as planned. Kim-sun stands outside their bedroom, filled with anxiety after the call.
