Episode 4 recap: The Angel Sanatorium Murder Case Solved.

Daming saw that Lin Mo played the piano every day and nodded in satisfaction. After Shama was released, he walked up to Lin Mo, glared at him fiercely, and made a cracking sound with his mouth. Peng Xi, witnessing this scene, reminded Daming once again, but Daming told her not to interfere and assigned her to prepare for the arrival of a patient. The patient was personally sent by the Health Bureau's leader and had acquired rabies. Peng Xi assigned him the codename "444."

When 444 was brought in, he had a mask on his head and his hands and feet were bound. Late at night, when it was quiet, Shama quietly sneaked into Lin Mo's room. He uncovered Lin Mo's blanket but found it empty. Lin Mo anticipated Shama's return and took advantage of Shama's momentary distraction to launch a sudden attack. However, even though he gained the upper hand, he was still no match for Shama. After just a few rounds, Shama subdued him and took out a rope from his pocket, strangling him.

Just as Lin Mo was about to die on the spot, 444 suddenly burst into the room and launched an attack on Shama. When Daming and his team arrived, Shama had already been beaten and was sitting on the ground unable to move. Daming wanted someone to detain 444, but even the security guards couldn't stand up to him and only ended up getting beaten.

After knocking down the security guards, Daming was trembling with fear. However, 444 didn't continue to pose a threat but instead accused Lin Mo's room, saying that he wanted to stay there. After 444 entered the room, Lin Mo expressed his gratitude, but 444 told him to thank Xiao Ai. Xiao Ai recognized Lin Mo's distress signal because relying on the police would require various procedures, and she was worried that there wouldn't be enough time. She found the bodyguard Kun Tai and had him impersonate a patient to protect Lin Mo.

After arranging everything, she went to the police station to find Jie Ke Jia. Jie Ke Jia brought his team, fully armed, to the Angel Sanatorium and rescued Lin Mo. Lin Mo led the police to the back mountain, where they dug up the body of a cherry blossom tree and discovered that the organs had been hollowed out.

Lin Mo accused Da Ming of using Shama and Sakura to kill innocent people indiscriminately and trafficking human organs. Da Ming vehemently denied the accusations. Since organ transplants need to be done within six hours, Lin Mo pulled up the surveillance footage of Sakura's death and discovered that Da Ming had driven to a dental clinic. After cutting off the clinic's connection, Lin Mo had a computer expert named Kiko examine the computer there. They found the entrance to the black market trade, and the Angel Rehabilitation Institute was where organ transactions took place. The money from these transactions ultimately flowed into an account called "King."

Sasha suspected that King was Da Ming. Da Ming's child and wife were in Australia, and his wife had a charitable foundation account. Sasha believed that King was using this foundation account to launder money. However, Lin Mo had a faint feeling that King was someone else. So she asked Da Ming who King really was, but he remained silent. Just then, someone ran over and informed Lin Mo that Shama was planning to kill Pengxi. Lin Mo hurriedly rushed over.

Six years ago, there was a mentally ill patient named Kata who killed five elementary school students, including one named Peng Xiaozhi, who was Pengxi's son. Upon meeting Pengxi, Lin Mo asked her about the reason Shama killed her. Pengxi told Lin Mo that her purpose for coming to the Angel Rehabilitation Institute was indeed to avenge her son. However, before she could act, Da Ming discovered her plans and used them to blackmail her. She had gone to confront Shama just now, wanting to ask Shama if Da Ming had ordered him to kill Number 414 and if Da Ming had used his granddaughter to threaten him. Shama might have been provoked by her questions, which is why he suddenly choked her.

As for who King really was, Pengxi had no knowledge of it. While the two were talking, piano music suddenly came from outside the door. Shortly after the piano music started, Sasha rushed over to inform Lin Mo that Da Ming had jumped off the building in a suicide attempt. Through Da Ming's suicide, Lin Mo suddenly thought of An Song. Prior to this, Lin Mo had instructed Kiko to infiltrate An Song's office and take pictures of his written novel. Lin Mo discovered that each story written by An Song had a real-life prototype, except for the one corresponding to King. Therefore, she suspected that An Song was King.