- The protagonist appears: the male protagonist Anli is a structural engineer at the Urban Architectural Design Institute and is professionally sensitive to construction safety; the female protagonist Haha is an emergency department nurse in a community hospital. She faces trivial patient needs every day and has an optimistic and tenacious personality.
- Foreshadowing: When Amway inspected dilapidated buildings in the old city, it found abnormal cracks in the walls, but reported the incident but did not take it seriously; Haha's hospital received many cases of "unexplained" dizziness and nausea, and they were concentrated in the old city area.
- Intersection occurred: Hahaha contacted Amway, who was responsible for house safety assessment, because of the physical examination needs of residents of dilapidated houses in the community. When the two met for the first time, they had differences of opinion over "whether dangerous houses should be evacuated immediately." Amway rationally emphasized data, while Hahaha was emotionally concerned about the safety of residents.
