In the sixth episode of "Concrete Market," the story resumes where it left off, with Chairman Park and Hee-ro discussing the elimination of Tae-jin. Hee-ro seems to agree, even suggesting that the Chairman speak with Cheol-min later in the evening to inform him of the plan and take over management of Tae-jin's section and his followers. Hee-ro offers to inform Tae-jin to head up to the Chairman's room at 9 pm that night.
It turns out that Hee-ro had a secret plan unknown to all the players. She had found a way to eavesdrop on Chairman Park's conversations in his room through the speaker he used for announcements. Earlier, when she left the room, she had suggested that he call in Cheol-min and update him on the plan to kill Tae-jin and take over his stores. Hee-ro had recorded their conversation using Se-hee's music player.
At 9 pm, Cheol-min takes one of his associates to finalize the plan by ambushing Tae-jin on his way to see Chairman Park. Meanwhile, Hee-ro waits for him at the stairs and replays the recorded conversation between Cheol-min and Chairman Park.
Tae-jin hears them planning to kill him because he overstepped. Cheol-min questions why Chairman Park wants to kill Tae-jin, knowing that he owes his life to him, and he simply mocks his stupidity, saying that he never gave Mi-seon any antibiotics to treat him. He only gave worthless vitamins. He admits that he helped Tae-jin because he thought he could help him manage things at the market, but because Tae-jin betrayed him, he no longer needs him.
Tae-jin is heartbroken after hearing their conversation. He wants to confront the chairman to clear up the misunderstandings, but Hee-ro leads him to believe the chairman will not listen. She convinces him to join their plan to take control of the ninth floor.
In this scene, the characters' motivations and emotions are clearly portrayed, and the plot thickens as each character's actions lead to unexpected consequences. The use of recorded conversations and eavesdropping adds a layer of intrigue and suspense to the story, making it more engaging for the audience.
Tae-jin's inquiry about Cheol-min unravels a complex web of intrigue as Hee-ro's carefully laid plans come to light. In a flashback, she ingeniously approached Chairman Park's informant within Cheol-min's inner circle, exploiting his vulnerability to blackmail him into executing her plan. The informant, plagued by debilitating migraines following his hearing loss, is coerced into agreeing to eliminate Cheol-min under the threat of exposing his secret ties to the Chairman. In return, Hee-ro promises him access to vital headache medication.
The chess match of plans and counterplans reaches its climax as Hee-ro's planted agent within Cheol-min's camp successfully executes the deed, convincing the boys to go along with the scheme. Meanwhile, Tae-jin agrees to collaborate with Hee-ro in their bid to usurp the throne and gain control of the ninth floor.
Just before the operation commences, Hee-ro returns to her room, briefing Se-hee about the impending turmoil and instructing her to remain indoors. However, Se-hee has some alarming revelations. While strolling through the market and overhearing whispers, she discovers a connection between Mi-seon and Tae-jin. Mi-seon's expertise in chemistry and knowledge of poisons raises suspicions. The fact that Se-jeong's death was accompanied by red rashes on her body suggests a possible poisoning. Se-hee posits that Tae-jin and Mi-seon were working together to make Se-jeong disappear in order for Tae-jin to secure her position as Chairman Park's lady.
Determined to verify Se-hee's claims, Hee-ro sneaks into Mi-seon's room, 802, where she stumbles upon a diary chronicling her child's life. The woman working on the eighth floor discovers her there, shocked by the contrasting story it reveals regarding Se-jeong's demise.
It transpires that these women are mothers whose children miraculously survived the earthquake and managed to reach the makeshift market. Chairman Park's decree that everyone must work to earn a living in the market did not exclude the children. He ordered them to crawl into the crevices of collapsed buildings, searching for food and other essential supplies. One fateful day, an aftershock struck, burying all the children beneath the rubble. Ever since, the chairman has distanced himself from the women without offering any apology or explanation, prompting them to wish for his demise in revenge. Se-jeong was assisting them in their quest for justice. On the night she died, she had obtained a vial of poison from Mi-seon, intending to put it in Chairman Park's food at dinner. However, something went awry, and she ended up losing her life.
Suddenly, Tae-jin rushes into the room to check on Mi-seon. He is shocked to find Hee-ro in the room, as Chairman Park had kidnapped a girl from room 109. It emerges that Chairman Park still doubted Hee-ro's plan to eliminate Tae-jin. He sneaked into her room to investigate further. Although Se-hee managed to hide when he entered, she left the room after Chairman Park and fell into his waiting hands outside.
At the end of the episode, Se-hee is found tied up in Chairman Park's room with her mouth covered in tape. Hee-ro realizes that the chairman had taken Se-hee into captivity.
