At nine thirty-six on a rainy night, a dog named Dahuang knocked on Lin Wan's door alone. Its owner Han Qingsheng has disappeared.
Surveillance showed that a few minutes ago, a man in a raincoat, whom everyone recognized as Han Qingsheng, had just walked through the square holding Dahuang. But the next day, Han Qingsheng's body appeared in the old bathhouse that had been closed for many years. What's even more bizarre is that the time of death presumed by the medical examiner is earlier than the "last appearance" in the surveillance.
The only dog that might have seen the murderer couldn't speak; the only person who remembered every lock in the old home was Lin Wan's father, who had suffered a stroke and was aphasic.
Thirty-seven keys, a repainted empty house, a signature left by a dead man, a brass wrench that suddenly disappeared, and a surveillance video that was twenty-four minutes and thirty-eight seconds slower...
Before Huaiyinli was completely demolished, Lin Wan had to understand the testimony that his father could not write, and he also had to find out - who was the person holding the dog in the surveillance video?
