Chen Ge didn't understand Dr. Gao's text message: "How is washing your hair related to self-protection?"

"The premise of post-traumatic stress disorder is that one has been hurt in some way. Men Nan washed his hair repeatedly in real life, most likely to get rid of some psychological trauma, which may be related to his past experiences."

"Previous experience?"

"Yes, his past experiences have left him with a strong psychological impact. Whenever he thinks back to it, or encounters similar things or sees similar things, his body will react. In order to relieve the pain, he will instinctively look for ways to comfort himself. According to the current situation, this method is washing his hair." After a while, Dr. Gao sent another text message: "When he first entered school, I asked Men Nan why he chose to study psychology. The child replied that he wanted to treat someone. Thinking carefully, the person he was talking about should be himself."

"It seems that the root of the problem is still in Men Nan's childhood experience. I think it is necessary to explain it to him clearly. Only when we know the cause and effect can we help him."

"If my speculation is true, then you can't ask him. He has been trying his best to avoid that incident. Now if you let him recall it bit by bit, I'm afraid he won't be able to bear the stimulation and will completely collapse."

"Then let's contact his family. It's unacceptable that his parents don't care when their child is in such pain." Chen Ge really wanted to take a photo of Men Nan's current appearance and send it to his parents so that they could see it.

"I asked about this when I called him a while ago. Men Nan has had a quirk of washing his hair since he was a child. His parents are used to it and don't think it's a serious matter."

"Didn't they tell me the reason for this habit?"

"No, when Men Nan was very young, his parents took him to see a psychiatrist, who diagnosed him with obsessive-compulsive disorder. This was very rare for his age, and considering the child was still young, no corresponding medication was given. The doctor just encouraged his parents to spend more time with him."

"It's obvious that his parents didn't listen to the doctor." Chen Ge replied without thinking. If Men Nan's parents really cared about him, their attitude would not be so cold.

"Mild obsessive-compulsive disorder won't affect his life, so his parents never paid much attention to it. In addition, after careful inquiry, I learned that Men Nan's biological mother was murdered when he was five or six years old. Later, his father remarried, and Men Nan has a younger brother."

"My biological mother was murdered? Is this true?" Chen Ge felt that the road that had been blocked had a new way out.

"The relationship between his biological parents was not good. His father was away from home all year round, and his mother raised the child alone. One day a thief broke into their home. Men Nan's current parents don't know what happened afterwards. They only know that the neighbors called the police the next day after the incident."

"The day after the crime?" Chen Ge's heart skipped a beat. "Then where was Men Nan when the crime happened?"

"I don't know where Men Nan was when the crime happened, but I know that when the neighbors called the police, Men Nan was at the crime scene. He was the first person to find my mother."

Looking at the text message sent by Dr. Gao, Chen Ge felt a chill running down his spine. "So Men Nan and his mother stayed at the crime scene for a day and a night? They were not discovered until the next day, right?"

"It can be understood that perhaps the criminals let Men Nan go, or maybe he was not at home at the time. In any case, Men Nan escaped by luck. But seeing this scene at such a young age must have had a great psychological impact on him. I suspect that his obsessive-compulsive disorder and current illness are related to the murder when he was a child. But I can't understand why he keeps washing his hair. Is there any connection between washing his hair and the murder?"

The doubts revealed in Dr. Gao's text message were exactly what Chen Ge wanted to know. He stood in front of the mirror and looked at himself in the mirror.

"Washing your hair? Self-protection?"

The scene of himself imitating Men Nan flashed through his mind. Chen Ge touched the back of his neck and suddenly thought of something: "Water droplets!"

He immediately sent a text message to Dr. Gao: "Criminal scene, where was the body of Men Nan's mother found?"

"After the criminals accidentally killed Men Nan's mother, they removed the moisture-proof board on the top of the bathroom and stuffed it in. If it weren't for the neighbor's child who often went to school with Men Nan and the two families had a very good relationship, they wouldn't have noticed the problem so quickly."

"The moisture-proof board on the top of the bathroom?" Chen Ge looked up at the bathroom where he was. The apartment building was very low, and living in it was very depressing. "I think I understand why Men Nan has an obsessive-compulsive disorder about washing his hair."

He took out his cell phone and texted Dr. Gao: "Do you think this situation will happen? After the thief breaks into the house, both the mother and the son discover the thief. The mother asks Men Nan to hide, and she secretly calls the police, but she is discovered by the thief."

"That's possible, but what does it have to do with washing your hair?"

"Men Nan watched his mother being killed and her body hidden. After the criminals left, he went to look for his mother. When he came to the bathroom, his mother's blood dripped onto his head." Chen Ge felt a little uncomfortable when he typed these words: "So until now, whenever blood dripped onto Men Nan's head, or he recalled the scene at that time, he would wash his hair over and over again, trying to forget those memories. Doctor Gao, what you said before was so right. Men Nan's condition is definitely not ordinary obsessive-compulsive disorder!"

After sending these words, Chen Ge looked outside the room. Dr. Gao in the bedroom had a shocked expression on his face. At the same time, he looked at Chen Ge in the bathroom. The two of them looked at each other in tacit understanding.

"We've found the cause!" Doctor Gao put away his phone and walked towards Chen Ge. "I'll take him away right now and start the corresponding traumatic disorder treatment."

"I'm afraid it won't work yet." Chen Ge looked at Men Nan who was standing there and shook his head slightly: "In the dream that Men Nan kept having, washing his hair was not scary. What really frightened him was the man who was getting closer and closer. If we want to help Men Nan, we have to find out everything about that man and drive him out of Men Nan's dream."

"Drive out the things in the dream?" Doctor Gao looked strange. He looked at Chen Ge, then turned back to look at Men Nan who was standing strangely. He felt like he was in the mental hospital for the first time. "Are you kidding me?"

"I already have a rough guess, and it will be verified tonight!" Chen Ge connected all the clues together, and he was 60% sure: "There are indeed three 'people' in this room. The identities of two 'people' can be confirmed. We just need to find the other one."