Why did Xu Mao and his daughter Zheng set fire to food?

In order to become the deputy secretary of the village department. In the book Xu Mao and His Daughters, Zheng framed Xu Mao's eldest son-in-law, Shuiyue, and removed Shuiyue from the post of village party secretary. Later, he set fire to Shuiyue's home, which indirectly led to the death of Xu Mao's eldest daughter. After Zheng became the deputy secretary of the village department, he abandoned Sisi and divorced Sisi. Later, the working group stationed in Huluba, fearing that the bad things they had done before would be exposed, pestered four girls to remarry.