When the sun reaches its highest point, its shadow disappears. Detective Han Dongxiu (Han Seok-kyu) becomes depressed after his son dies accidentally in order to confirm his suspicions about a murder case that has already been concluded. 14 years later, a murder case seems to have some connection with the case. When Han Dongxiu begins to pay attention to the son of one of the victims, Youhan (Gao Xiuxiu), he accidentally meets a private detective who is helping the boss of the consortium investigate his fiancee Liu Meihao (Son Ye-jin). He learns from the private detective that the woman named Liu Haomei is the daughter of the murderer who was believed to have committed suicide out of fear of crime. The two children that Han Dongxiu once suspected have now grown up and are around him because of the murder case. During Han Dongxiu's investigation, he discovered the truth of the murder case and the recent murder case. Behind the truth is a pair of bitter lovers who can never meet in broad daylight. The film is adapted from the novel of the same name "White Night Walk" by the famous Japanese mystery novelist Keigo Higashino. The novel was made into a TV series in Japan and was a huge success.