The drama is adapted from the novel - The Shadow Envelope.During the turbulent times of the Republic of China, the situation was turbulent, and three powerful people in the city were mysteriously killed.

Faced with the police station's actions that the senior officials wanted to make things hastily, young police officer Shen Yan took the lead and insisted on investigating the case.

The truth is confusing, and as layers of fog clear away, a conspiracy spans across twenty years has been unveiled...