The Bullet Vanishes (2012)

"During the Republic of China, a bizarre murder occurred in the country's largest arsenal. The deceased was killed by a "ghost bullet" - no warhead was found at the crime scene. Suddenly, suspicions abounded and people were panicked. This case was regarded as the most bizarre case in the Republic of China. The case was handed over to Songdong Road, a political police officer responsible for managing files in the police station, for investigation (played by Liu Qingyun)..."