Episode 4 recap: Song Yun Hui went to the town for an investigation.

During his return, Song Yun Hui learned about the imprisonment and imminent execution of the people in the factory. He planned to make the people around him reveal the entire process of poisoning, but they felt that it was futile. However, reaching a conclusion was not easy at the moment. Song Yun Hui was prepared to cooperate fully with the subsequent work and try to bring Wang Qiang to justice. Upon hearing this, the people around him hurriedly prepared to find evidence. Unexpectedly, Song Yun Hui believed that direct evidence was not enough to prove that the other party did not poison, and the key was to successfully find the true source of the poison.

On the other side, Yang Xun was helping others with the moving process. Liang Si Shen called, and he immediately stopped what he was doing and ran to meet her. They walked around outside, chatting and laughing along the way. Gradually, they made their way to the rooftop, where they admired the beautiful scenery. Liang Si Shen couldn't help but take some photos. Afterwards, she actively expressed her intention to use the money from selling her house in the United States to participate in investments. However, when the other party heard the amount of shares she held, their true thoughts were revealed. After reaching an agreement, they both began to prepare for their respective tasks.

Afterwards, Liang Si Shen drove to the entrance of the factory and spoke to the security guard about her plan to meet Director Song Yun Hui. Surprisingly, the people inside the factory told her about his visit to the town. On the other hand, Song Yun Hui was busy running around alone, inquiring about the situation with the villagers. However, nobody wanted to pay him any attention, and as soon as they heard him asking about poisoning, they hurriedly tried to send him away. Liang Si Shen, who was looking for her teacher on the side, felt uncomfortable witnessing this situation and proactively went over to greet him.

After meeting each other, they sat down and had a meal together. At the dinner table, Song Yun Hui explained in detail everything that had happened in the factory. Although some of the employees had turned themselves in, he believed that the situation was not as simple as it seemed on the surface and that further investigation was necessary.

After leaving, they continued to visit the villagers' homes. Liang Si Shen also noticed the health condition of a child nearby and decided to take them in her car to the hospital for medical treatment. In this situation, they continued to be concerned about the villagers' drinking water issue and prepared to investigate the situation thoroughly. However, to their surprise, when the members of the investigation team found out that Song Yun Hui had leaked the information, they started blaming him. This time, Song Yun Hui was prepared to face the consequences alone and suggested suspending the water source. However, the others disagreed with his proposal. After reaching a unanimous decision, they resumed their investigation and worked diligently to implement their plans. Before leaving, the people around him reminded Song Yun Hui to carefully investigate the water contamination issue.

Upon returning, Song Yun Hui took the opportunity of the night to call Director Cao and others to prepare a detailed wastewater discharge report. While busy with this task, he suddenly learned about the poisoning incident from people outside. In a hurry, he got into the car driven by Liang Si Shen and rushed to the scene to assess the situation. After entering, Song Yun Hui gathered information from nearby villagers and proceeded to the granary.

After interrogating the individuals involved, Song Yun Hui planned to confirm the specific type of pesticide they used, as well as the methods of application. After analyzing the information, he informed those around him that the collective poisoning incident in Shuitou Town might be related to the granary. The members of the investigation team who received these clues were prepared to continue their pursuit. Once they made significant progress in the investigation, Song Yun Hui returned in a student's car, expressing gratitude for the assistance provided.

At home, when Lu Hongwei was preparing to leave on his motorcycle, he was unexpectedly approached by Sibao asking for help in replenishing supplies at the printing factory.