Zhang Chenggong is the deputy director of the county public security bureau. He is Xiao Yuan's former comrade-in-arms from their military service. After demobilization, he was assigned to the county public security bureau and is described as a very upright and honest-looking person. When Su Yun contacts him, he immediately puts down his work and comes over to help. He understands Su Yun's situation and leads her to a trustworthy leader who reviews her evidence. He is decisive in ordering the arrest of Qin Aiguo and sending a full team to investigate the Qianjin Brigade. He understands Su Yun's need for confidentiality and ensures her safety while keeping the report confidential. He thanks Su Yun for her courage in reporting the crimes.
