It turned out that Xu Qingqing had been sick before, suffering from an incurable cough. Eventually, she had been referred to a Gu Master from the Miao Borderlands, who had cured her illness.
However, during this process, she witnessed the Gu Master's method of treatment, which involved implanting live insects into a person's body. She had also seen with her own eyes how the insects tore into the flesh and crawled out of the body.
Even though her illness was cured, the experience had terrified Xu Qingqing half to death. Moreover, after the treatment, the Gu Master didn't ask for money but instead assigned her the task of collecting Tang Hao's hair. If Xu Qingqing failed to follow the instructions, the Gu Master threatened to send the Gu insects to torment her beyond endurance.
Frightened into compliance, Xu Qingqing dared not disobey.
