Hogwash oil generally refers to recycled waste oil which is haphazardly processed into inferior cooking oil. This oil is far more toxic than arsenic and even contains carcinogenic substances. However, three million tons of hogwash oil in China sneaks back to dining tables each year thus endangering the health of citizens. Why is there such a dirty cycle? Is it because of the inadequate government supervision or the tempting profit that causes the food industry to go astray? In order to look for a cure to this malignant tumor, our reporter probed into the problem through secret visits and interviews with related parties, trying to unravel this chain of deception which is worsening the food safety problem in China.