Sara meets Ji In, who explains that since Professor Seo's phone was destroyed, they need to find another piece of evidence. Ji In then hands her a file containing information about the Five Member Society, and mentions that they have bribed many people to advance the Cha Yul Town plan. Sara takes the file back to Solution, and they decide to locate the ledger listing the bribes. They learn that the fund manager of the Five Member Society is Jong Il, a reporter for Myung Il Newspaper. He is greedy and willing to write anything for money. Jang Mi arranges for him to come to her restaurant to write a favorable review, after which Kang Bom and Dae Ki are tasked with giving him a bag of money, which contains a tracking device. They follow the signal to a piece of agricultural land owned by Cha Yul. They were about to dig with shovels, but Sara stops them because Jang Mi has brought a digger. After some digging, they only find the container with the money they gave to Jong Il, but the bribery ledger is missing. They enter a nearby house and finally find the ledger by evening. Meanwhile, Yul Seong finds out that Jong Il has written an article for Jang Mi's restaurant and calls him to inquire. They quickly realize they have been deceived by the Solution team. The other members are very angry and plan to beat up Jong Il. However, Yul Seong has another way to threaten Sara; he has someone pick up Seo Yeon from kindergarten and calls Sara to demand the ledger back. At this time, Sara is at the police station and about to hand it over when she learns that Seo Yeon has been kidnapped. Yul Seong threatens that if she hands it over to the police, she will never see Seo Yeon again. Gi Jun says they can track Seo Yeon using the tracker on the boy's secret phone. Sara asks him to find Seo Yeon while she goes to confront Yul Seong. Sara calls Yul Seong trash for willing to kidnap her own child as a way to threaten her. She shows him the ledger and opens it to prove it’s real. At that moment, Yul Seong’s henchman brings Seo Yeon to the exchange point, with Gi Jun following them closely. Sara throws the ledger towards Yul Seong, who releases Seo Yeon. Gi Jun quickly drives Sara and Seo Yeon away, while Yul Seong realizes that only a few pages in that ledger are real and the rest are just blank paper. The real ledger is soon handed over to the police and the prosecutors, and the bribery case involving Yul Seong and his society is exposed. Sara and Gi Jun try to persuade Yul Seong’s assistant to testify about Yul Seong pushing Sara’s mother, but he refuses. The next day, Jin Won leads the investigation into the bribery case related to Cha Yul Town and conducts a search at Cha Yul. Yul Seong tells his assistant that if he’s asked about the day Sara's mother died, he must say that Yul Seong was not in the car going to the construction site, and that he was the one who drove Sara's mother there. Realizing that Yul Seong is ready to throw him under the bus, the assistant changes his mind and testifies that Yul Seong did push Sara's mother. Soon after, the Cha Yul Town project is canceled, and the Solution team is overjoyed. That night, Sara receives a call from Yul Seong arranging a meeting. She agrees to meet him, hoping to secretly record him confessing to killing her mother. However, this turns out to be a trap set by Yul Seong to harm Sara. He uses a cloth soaked in an anesthetic to knock Sara unconscious. Later, he takes her to a secret house, where she is tied up and gagged.

After a while, Yul Seong unties Sara and offers to release her if she publicly lies that the bribery ledger is fake. Sara ignores him and repeatedly demands that he confess to killing her mother, but he steadfastly denies it and begins to get physically aggressive with her. A concealed recording device falls from Sara'pocket, which Yul Seong immediately destroys.

Unbeknownst to him, the night before the meeting, Sara had devised a plan with Gi Jun and the Solution team to use herself as bait, with the team ready to follow closely and support her. However, at this point, Yul Seong has destroyed the communication device.

Later, Yul Seong drags Sara out of the house and into a car. He intends to take her away, but discovers that the car's tire has been slashed. Unknown to him, his car also had a tracking device, and Sara takes this opportunity to inform the Solution team that Yul Seong is planning to take her to a warehouse.

Yul Seong switches to another vehicle and takes Sara to a shipping port, where he locks her in a refrigerated shipping container. Meanwhile, the Solution team arrives at the house and finds a memory card that Sara had hidden in the slashed tire car of yul seong.

Meanwhile, Yul Seong forces Sara to endure the cold and threatens her that if she doesn't make a false confession to his phone recorder to help him avoid charges, he will lock the container door and she will die from the cold. Despite the harsh conditions, Sara refuses to give up. As a crane approaches to move the container onto a truck, Sara questions Yul Seong again about her mother's death. This time, thinking Sara will die anyway, he admits he didn't intend to kill her mother but accidentally pushed her.

sara is enraged as Yul Seong nonchalantly walks away after giving her a knife to cut her ties, but he locks the container door behind him. Sara quickly frees herself. Meanwhile, the Solution team arrives at the warehouse and begins a difficult search among numerous containers. Fortunately, Gi Jun finds the container holding Sara and rescues her from near death.

As Yul Seong is driving away from the port, he is stopped by Prosecutor Jin Won and his colleagues. Sara and the Solution team quickly arrive at the scene. Sara rushes to Yul Seong, knocks him down, and retrieves the phone that recorded everything, including his admission of killing her mother. The prosecutors move to detain Yul Seong.

A few days later, Sara and Seo Yeon visit her mother's grave. Gi Jun joins them and promises Sara's late mother that he will look after Sara and Seo Yeon as if they were his own family. Later, Sara and Gi Jun shop for wedding rings but reveal they are for Dae Ki and Kang Bom's wedding, with Sara officiating the ceremony.

After the wedding, Gi Jun proposes to Sara and confesses his feelings. Although touched, Sara tells him she wants them to live together for five years and then separate, believing that marriage has an expiration date. However, if they still wish to be together after five years, they could marry then and become lifelong partners.