Tang Chengcheng and Zheng Xiaohu attempted to obtain information about Teacher Zuo from the security guard, but the guard stated that they only started working seven years ago and knew nothing about Teacher Zuo. Tang Chengcheng noticed that the arrival of the security guard was close to the time when Teacher Zuo went missing. Qixia and Sinan investigated the bidding situation of the plastic playground renovation project at Fengming Middle School and found that the winning company, Company A, was cancelled shortly after winning the bid, and the legal representative, Yan Ping, later opened a restaurant. Tang Chengcheng thought of the principal's wife being called "Teacher Yan" and suspected that "Yan" may be Yan Ping's surname, and that Yan Ping and the principal's wife may be related.

Chapter 9: Catching Grass and Startling Snakes

Zheng Xiaohu proposed to confirm the identity of the fugitive through DNA testing, but Tang Chengcheng pointed out the lack of operability. Sinan cleverly obtained Yan Ping's mobile phone number through the phone, demonstrating the way adults solve problems.