This is a residential building commonly found in the urban district, capped at five stories, with just a few households residing within. A large black dog always squats in the corner by the entrance, standing up to bark furiously at anyone passing by, a sight people have grown accustomed to.
But tonight, things have become far from ordinary: the black dog whimpers miserably, its voice sounding weak and breathless, chilling to the bone; the residents inside all huddle with their families, their faces etched with terror as they look towards the ceiling overhead.
In that corner, a patch stained by sewage spreads recklessly, its color deep and rich like oil or tar, with viscous liquid occasionally dripping down. From the fourth floor to the first, at the very same spot vertically, there is such a stain, neither too big nor too small, tracing its source...
To the only household on the fifth floor.
