Introduction：Zhang Northwest, who was determined to become a detective, crossed back to Shanghai Beach in the 19th year of the Republic of China through a toilet by chance. He was imprisoned for being falsely accused of 'killing' Xu Wenqiang, while his friend Jia, who had also traveled through timeThe help from the southeast enabled the escape from prison. Zhang Northwest, in order to clear his name, tracked a witness at the scene - Ming Pao journalist Du Xiaofei. He also met his girlfriend Xiao Nan, but shared the same body with Lu Yiping. Only when he heard thatZhang Northwest only remembers the past when he says' break up '. Zhang Northwest was eager to clear his name and help Xiao Nan regain his memory, but he was unexpectedly caught up in the murder case of Lu Daping.