After Zhao Jianguo injured himself cutting firewood, he remained bedridden for half a year, relying entirely on the village doctor, Sun Gui, to dispense medicine and recuperate. One day, Li Xiumei knocked over a bowl of herbal medicine, and the family's eldest dog, Huang, died on the spot from poison after licking it, making her suspicious of the medicine. Keeping it a secret from everyone, she quietly carried the medicine packet far away to seek help from the veteran doctor Zhou Defu, who confirmed that the medicine was mixed with the chronic lethal poison datura. Long-term consumption would hollow out organs, paralyze the heart and lungs, and cause a death resembling a heart attack. Tracing the past, Li Xiumei learned that Sun Gui harbored a deliberate revenge due to a grudge between their fathers, and that a villager, Wu Dazhu, had already been poisoned and killed by him after catching him hiding prohibited drugs in his cellar.