In 2004, "Who's the culprit" was played by Xiao Hui: Tan Xiaoou's Interpol captain Li Yi took his dog Dabao out for morning exercises, and Dabao was enjoying cherry blossoms.

A female body was found in the grass in the community. Due to professional habits, Captain Li blocked the crime scene while reporting to Director Gao. With him is Tan Xiaoou, a new assistant given by Director Gao to Li Yipai, a graduate of the Public Security University and a second-class superintendent.