Chen Jingshan, an old clockmaker in Jiangcheng, was killed. All the clocks at the scene stopped at three-seventeen, and the deceased held half of a special gear in his hand. Interpol Lin Mo's investigation found that the case was related to Qin Zhengguo's espionage case more than 30 years ago and a missing clock from the Republic of China. The clock hides a secret. Chen Jingshan's diary and clues from the clock tower reveal that the murderer came to seize the secret. As suspects such as Zhou Mingyuan emerge, and clues such as the old Passat and mysterious symbols are intertwined, Lin Mo gradually approaches the truth and the real murderer that spans decades.
