Chen Mo, a former detective who retired due to post-traumatic stress disorder, was forced to return as a consultant. He hides a secret: he can hear the vague echoes of the dead's last moments - coldness, falling, a broken melody. Lin Han, the newly appointed criminal investigation captain, sneered at this. She only believed in ironclad evidence and logic. A series of unsolved cases tied them together. He stumbled forward in the darkness with the help of sound fragments, while she illuminated every chain of evidence with absolute rationality. When the clues of the case quietly point to the dusty old case, that is the starting point for Chen Mo to fall into the abyss. The murderer is still in the dark, and every time he "listens", he accelerates his collapse. Until that time, when he went into danger alone to protect her, and when he was on the verge of drowning in the echo of death, he heard a clear sound - it was her anxious heartbeat as she ran towards him desperately.
