In a small coastal town shrouded in sea fog, the famous psychiatrist Chen Yuanshan was found dead in a closed consulting room. The doors and windows were locked, the key was in the deceased's pocket, and there were no signs of breaking into the door - a perfect locked-room murder case. On the notebook in front of him, a clock was drawn with trembling handwriting. The hour and minute hands pointed to twelve o'clock, but the dial on his wrist showed three o'clock in the morning. Is this three-hour time difference a carefully designed deception by the murderer, or is it a clue to the truth left by the deceased in his desperate attempt?
Criminal psychology expert Shen Du was ordered to intervene in the investigation. He soon discovers that this respected psychiatrist has been hiding a secret about lies, betrayal and atonement for the past six years. And everyone who is close to the truth has lost their way in the fog.