Three months later, Old Zhang, a septic tank emptier in the capital, has not come out to work for many days, and everyone's toilet is clogged and unusable. Zhu Yi Pin and Yang Yu Xuan go to Old Zhang's house to look for him, but they find that Old Zhang has been burned to death at home. Zhu Yi Pin examines the body of Old Zhang, and he feels that Old Zhang's burns are strange. His body is already burnt to a crisp, but there is not a bit of black smoke in his mouth, and there is no fire in the room. (Source: Viu)