How did Chang Hao know Xiaomei?

Police station. Chang Hao and Xiao Mei are important characters in the TV series Slang Lawyers. In the plot, they first met at the police station. Slang Lawyer is a TV series directed by Wu Zhonghuan and starring Lee Jong Suk and Lin Yun A, which tells the story of a third-rate lawyer with a winning rate of only 10% who is involved in a series of strange incidents with his wife after taking over a murder lawsuit.