Because Hu Xingguo held a grudge against Zhang Huaizhong for stealing his wife, he deliberately sold the problem milk produced by Zhang Huaizhong's Caiyun Food Factory in the city. By a twist of fate, the drivers for Caiyun Food Factory and the city's Niangniang Dairy had the same surname and made deliveries on the same day, so the milk was mistakenly delivered to each other's hotels. The problem milk from Caiyun Food Factory poisoned many guests attending a wedding at the Lishangwanglai Hotel, sending them to the hospital. Zeng Guanying of the Market Supervision Bureau was ordered to investigate, but encountered obstacle after obstacle. After someone died of poisoning, the city formed a special task force. Its investigative team consisted of the Market Supervision Bureau and the City Public Security Bureau. Zeng Guanying and Zheng Hongwei of the Public Security Bureau joined forces, leading a team in a thorough investigation. Along the way, they faced setbacks and misunderstandings, as well as a thrilling undercover operation, an escape, and a pursuit. In the end, they found Zhang Huaizhong, who had been making and selling counterfeit goods. Sadly, he had died while saving someone. The government officials who had colluded with him and the sales manager who had betrayed Niangniang Dairy were brought to justice.