Episode 4 recap: Liu Xiao Yu died in a car accident.

In the Pethun and Chopra case, the on-duty police officer was dismissed and punished, and as a police captain, there were also major work mistakes. However, he promptly apprehended Chopra, which could be considered as making up for his mistakes. So he could be considered for a one-year probation. Ge is very sorry that his own mistakes led to the officer being punished, but the officer did not blame Ge for it.

Liu Xiao Yu's landlord could not stand his bugs anymore, so he wanted Liu Xiao Yu to move out. Liu Xiao Yu almost got into a conflict with him, but Tan Jing Tian heard the argument and came out in time to persuade him, preventing Liu Xiao Yu from laying a hand on the landlord.

Afterwards, Tan Jing Tian apologized to the landlord, hoping he could understand Liu Xiao Yu, and even gave him a bottle of perfume. The landlord was initially unwilling, but after smelling the perfume and seeing Tan Jing Tian's sincere apology, he accepted it. Tan Jing Tian found a medicine bottle by his senior's bedside, and he knew his senior had a history of vomiting. He also confessed that he was taking medication, as they were both going through a depressive state, which was why Liu Xiao Yu's emotions were unstable.

Liu Xiao Yu told Tan Jing Tian that the reason he didn't want to do research with Professor Tang was that he didn't want to see more beautiful butterflies disappear from this world. Tan Jing Tian informed Professor Tang and Li Guo about Liu Xiao Yu's situation. Professor Tang was very surprised, as he didn't realize Liu Xiao Yu had reached this point, and Li Guo felt somewhat guilty, feeling that they had overlooked Liu Xiao Yu's feelings.

Tan Jing Tian thought of letting Liu Xiao Yu return to his home country first, as it might help his condition, but Professor Tang seemed reluctant to let Liu Xiao Yu go back. Professor Tang asked Tan Jing Tian to call Liu Xiao Yu the next day to go to Liming Temple together, to hold a small memorial service for Professor Song, as it was his death anniversary, and it would be good for everyone to be together.

The next day, the landlord was found dead in his own bed. Tan Jing Tian and the others did not yet know the situation, and they were waiting for Liu Xiao Yu at the appointed restaurant. They saw Liu Xiao Yu, but to their shock, they witnessed him being hit by a car and killed on the spot while crossing the road.

Witnessing the accidental death of a good friend may be the most painful thing in the world. And Tan Jing Tian seemed to feel that he was the one who had brought harm to his senior, because he has always been the "Detective Conan" type, and the people around him seem to keep dying in accidents.

At the police station, Jin Ling accompanied Professor Tang and Sister Li Guo. They learned from the police that the driver responsible was a 25-year veteran driver who had moved to Bangkok 5 years ago. The accident happened because he was distracted by the GPS on his phone and mistook the gas pedal for the brake, leading to the tragic incident.

Jin Ling found it strange that an experienced driver would make such a basic mistake. After leaving the police station, Tan Jing Tian decided to commit suicide by jumping off a building, but luckily Jin Ling went to find the officer, who used Tan Jing Tian's phone to locate and rescue him just in time.

In fact, the officer was not just there to save Tan Jing Tian. Two people had died in the officer's home within a day, and the officer's fingerprints were found in the victims' room, so he needed to bring Tan Jing Tian back to the police station for questioning. The officer let Tan Jing Tian stay at his home under 24-hour supervision, and in exchange, Tan Jing Tian agreed to cook Chinese meals for the officer, with Jin Ling also offering to help.

At the police station, Tan Jing Tian sat in on the discussion about Jirayu's death. The current conclusion was that Jirayu was poisoned, but it was unclear whether it was suicide or homicide. Tan Jing Tian's fingerprints were found on a perfume bottle in Jirayu's room, and he explained that he had given the perfume to Jirayu. Tan Jing Tian then thought of insects, but the police did not find any at the scene initially. After the officer had them re-examine the crime scene, they discovered a lizard that a colleague had taken home, thinking it was insignificant. This turned out to be a crucial clue, as Tan Jing Tian recognized the ants in the lizard's habitat as one of the most poisonous insects in the world.