In episode 7 of "Concrete Market," the story unfolds with Se-hee, tied up in Chairman Park's room. As the situation escalates, Hee-ro, Tae-jin, and the women on the eighth floor devise a plan to rescue Se-hee and take revenge on Chairman Park.
Tae-jin proposes that they can rescue Se-hee when the water starts flowing, as Chairman Park's men will rush downstairs to drink water. However, Hee-ro's plan to fix the water pipes falls flat, leading to disappointment. But they find a way around it by using the water in room 209 to lure the men away. They funnel the water into the pipes, and when the guard notices the running water, he rushes to inform Chairman Park.
The Chairman and his men leave their posts to have a drink, leaving the ninth floor unguarded. Hee-ro sneaks in to rescue Se-hee, who joins the women in Mi-seon's room while she stays behind to stock up on insulin.
Mi-seon provides the poison, which they use to poison the water in Tae-jin's room before pouring it into the pipes. Chairman Park and all his men unknowingly drink the poisoned water. When he realizes that he left his room unguarded, he rushes upstairs and confronts Hee-ro. He also sends some of his men to capture the women in Mi-seon's room.
The youngsters, led by Tae-jin, ambush the rest of the men. Both his friends and Cheol-min's boys work together. Chairman Park learns about the poisoned water from Hee-ro. His lackey, who followed him back to the room, suddenly vomits blood and falls to his death. The same happens to the men who went after Se-hee in Mi-seon's room and those Tae-jin was fighting.
Chairman Park doesn't go down without a fight. He strangles Hee-ro so that she almost passes out. Mi-seon and the women break down room 902 to get him off Hee-ro. He is still breathing, which gives the women the chance to get their revenge when one of them bashes his head in with a sledgehammer.
The episode ends with Se-hee and her allies victorious, but at a heavy cost. The story of revenge and betrayal continues to unfold in "Concrete Market."
After Chairman Park's demise, the concrete market continued to function smoothly, with the survivors continuing their barter trade to meet their needs. Tae-jin and the boys remained in charge, but their roles shifted from tax collection to enhancing the residents' lives. Hee-ro even proposed starting a school to reclaim the civilization that existed before the apocalypse.
Se-jeong's death was a tragic consequence of her hatred for Chairman Park, who had taken advantage of her vulnerability to force sexual relationships. In secret, she was working with Mi-seon and other women seeking revenge for their children. On the day of her demise, Mi-seon gave her poison to put in Chairman Park's dinner. Se-jeong managed to poison the food, but unfortunately, Chairman Park realized she hadn't added cheese. She took the plates and drizzled cheese on them, and when he put them on the table, he inadvertently placed the poisoned plate on Se-jeong's side. Realizing she had eaten the poisoned plate, she chose to jump from the building, hoping that her public death would stir something and encourage people to stand against Chairman Park's exploitation.
Hee-ro came clean about everything she had done, including setting up Tae-jin to be killed by Chairman Park. Mi-seon helped them understand that she was doing all that because she had someone she needed to protect. At the end of the episode, she was happy and had a good relationship with Tae-jin. She looked around the market and saw Se-jeong standing on the roof, smiling back at her. She had kept her promise. She had protected Se-hee and gotten revenge for Se-jeong's death.
