The shocking truth was revealed that Go Eun-seol (played by Jun Hye-won) is not biologically related to her family.

First, Park Hee-jung (played by Seo Yoo-jung) confessed the truth she had long hidden to Go Eun-guk (played by Park Sung-gyu) and Go Gi-han (played by Choi Jae-won). Hee-jung revealed that after her own biological daughter, who was born premature, passed away, she raised another child in her place. In the past, Joo Ae-sook (currently Joo Mi-ran, played by Jang Seo-hee) disappeared after giving birth, and Hee-jung took in the child who was about to be sent to a protective facility and raised her as the family's daughter. Wang Geum-ja (played by Seo Kwon-soon), who overheard this by chance, reacted with fierce resistance, saying, "So you're saying Eun-seol is a child you picked up off the street?" and strongly objected, asking, "Are you really going to raise a child whose bloodline you don't even know?"

Meanwhile, Joo Mi-ran's cunning behavior, using any means necessary, continued. When a friend's drama casting fell through, she tried to find a weakness in the actor who had taken the role. Additionally, when Kang Hae-ra (played by Ju Sae-byuk) became anxious after belatedly learning about the existence of CCTV cameras at school, Mi-ran volunteered to act as her guardian and headed to the school in her place after Hae-ra was summoned by her homeroom teacher. After checking the footage containing evidence of Kang Hae-ra's crime, Mi-ran approached the vice principal and demanded the deletion of the CCTV footage, promising to guarantee the vice principal's promotion to principal. The vice principal ultimately agreed.

The full details of the school fire incident, in which Go Eun-seol nearly lost her life, were also revealed. Kang Hae-ra lured Eun-seol, who was preparing her submission for an art competition, outside the school, then stayed behind in the art room and vandalized Eun-seol's artwork. During this process, lacquer came into contact with a light and caught fire, and the flames spread rapidly. Upon seeing the fire, Kang Hae-ra abandoned the scene without taking any action. Eun-seol, who returned to the classroom later, belatedly discovered the fire. Eun-seol went inside to protect her artwork and tried to use a broken fire extinguisher, but the exit was blocked by a fallen shelf. While attempting to escape by breaking the window, she cut her neck on glass fragments and ultimately lost consciousness inside the classroom.

Cha Seok-jin (played by Seol Jung-hwan), who had returned to the school out of concern for Eun-seol, discovered the fire scene and barely managed to rescue the collapsed Eun-seol. Eun-seol, transferred to the hospital, required a massive blood transfusion, at which point her blood type was confirmed to be Rh-A. With the fact that all family members are type O coming to light, real questions arose about the blood relationship between Eun-seol and her family. Seok-jin actively requested blood donations and blood support online, and thanks to this, Eun-seol overcame the crisis and regained consciousness.

However, the true culprit of the fire had not yet been revealed. Eun-seol explained that she was not the arsonist, but no one believed her, and she was eventually driven to the brink of expulsion. With the secret of her birth, the fire incident, and family conflicts intertwining all at once, another trial loomed for Eun-seol. Meanwhile, Eun-seol was the first to notice, through the blood transfusion consent form and blood type-related documents, that she might not be biologically related to her family. When Eun-seol cautiously asked Hee-jung, "Am I not your daughter?" Hee-jung warmly comforted her, replying, "Nothing changes. You are my daughter."