Wang Hao went up the stairs to the second floor and disappeared in a twinkling of an eye. I found some footprints at the corner of the stairs. Look at the lines on the footprints, it seems that Wang Hao left them. Because among so many of us, only he wears a special pair of sneakers, which is very easy to identify. The stairs are not as clean as the first floor, and they are covered with a thin layer of dust, so the footprints are very clear and can be seen at a glance.

There was no light in the black paint on the second floor. I stood on...