The System’s book contained this plotline.
Gu Qingya had been going to the black market to sell large quantities of goods; they were high-quality and cheap, and she had even developed a network of buyers. However, her operation grew too large, and she caught the eye of the black market boss. Although Gu Qingya took precautions and wore disguises every time she went, she had been tracked from her very first trip—the same time Song Zhishu played the hero and saved the damsel, which led to him being hospitalized—and she remained a target.
Later, Gu Qingya managed to trick the people tracking her and had them sent to prison to face the firing squad. But the man she sent away wasn't the real boss; he was just a small-time subordinate. Since she had acted so arrogantly, the real boss wouldn't let it slide; he wanted to wipe out both her and her goods. After having his men observe and track her for a long time, they finally confirmed that she was a sent-down youth living alone in Qingshui Village.
Chapter 156