Episode 1 recap: Tan Jing Tian becomes a murder suspect shortly after arriving in Thailand.

A murder occurred in a red-light district in Thailand, where a female victim was found dead in her bed by a foreign man who was terrified and reported it to the police while running away. The police quickly arrived at the scene and discovered lacerations on the victim's back, suggesting she had been stabbed.

Jin Ling, a forensic scientist, was dispatched to Thailand for an exchange program and happened to be assigned to assist with this case. Since the hotel where the incident occurred had no surveillance cameras, they had to rely on forensic evidence and investigation to solve the case. All the residents of the hotel were taken to the police station for questioning.

Jin Ling was surprised to see her boyfriend Tan Jing Tian at the scene. Tan Jing Tian explained that he was there to find a taxi driver and retrieve his luggage, and did not expect to encounter this incident. The police officer, Cha, and his colleagues were observing the situation, but Jin Ling trusted Tan Jing Tian's account.

However, the fact that Tan Jing Tian had been to the victim's room still made him a suspect. Tan Jing Tian recounted his experience - he had taken a taxi at the airport, but the driver had suddenly sped off in response to a phone call, and when they arrived at the crime scene, the driver disappeared and the trunk could not be opened. Tan Jing Tian went into the room to look for the driver, but only briefly looked around and left without finding him.

Cha was skeptical about how Tan Jing Tian knew the driver would be in that particular room. Tan Jing Tian explained that he had noticed the driver's necklace, which had a butterfly pendant, and was interested in it as an entomology graduate student visiting Bangkok Agricultural University. However, Cha did not understand the significance of the butterfly pendant.

Tan Jing Tian was eventually cleared of suspicion. As he was preparing to leave the police station, he happened to encounter the taxi driver, who was also the one who had reported the crime.

Officer Cha remained suspicious of the driver and asked him to look into his eyes and deny killing the victim, but the driver could not. Cha then ordered the driver to be detained. Tan Jing Tian paid the driver his fare and told him he didn't need any change.

Tan Jing Tian's senior classmate, Liu Xiao Yu, came to pick him up to go to their shared accommodation in Thailand. On the way, Tan Jing Tian discreetly inquired about how Liu Xiao Yu was doing, and when the conversation turned to their academic work, Liu Xiao Yu seemed hesitant.

Tan Jing Tian sensed something was off, but didn't want to pry. Meanwhile, Officer Cha brought Jin Ling to examine the remains of a body that had been burned 15 years ago, a case that had never been solved. Based on the witness' description, Cha dispatched his colleagues to apprehend a former police officer named Phathun as a suspect.

At the police station, Phathun was shocked to see the photos of the murdered victim, Sachu. He admitted to knowing Sachu but denied killing her, and broke down in tears upon seeing the photos of her injuries. Cha took Phathun to confront the detained taxi driver, but the two did not recognize each other.

Phathun explained that he and Sachu had been in a mutual romantic relationship, not one of financial exchange. As Phathun went to the washroom, he unexpectedly saw the taxi driver suddenly drop down from the ceiling above, staring at him with a strange, eerie smile.