The orphan Lin Mo grew up in the Bangkok Child Welfare Institute and sneaked out of the institution at the age of thirteen. By chance, he saw a killer and a scavenger assassinate and dispose of the body. The killer wanted to kill people, but was stopped by the scavenger old fish. When the old fish saw Lin Mo’s strong sense of smell and keen observation, he rejected him. Gradually, Lin Mo also became a scavenger. After growing up, he learned that he and his master were both controlled by a behind-the-scenes boss called “Smile”, and “Smile” would assign tasks to the two from time to time. All they have to do is deal with the scene of the killings, without knowing the true identity of the “smiling face”. Once, Lin Mo was indecisive when dealing with a murder scene, which caused Master Laoyu to be exposed, and was “smileed” ordered to be killed. Lin Mo’s death was a great blow to Lin Mo. He vowed to find a “smiley face” to avenge Master. In order to hide his identity, he went to Luming Middle School to become a chemistry teacher, and the recent “Pad apartment suicide case” and “writer murder case” have brought him a “smile” one step closer.

After seeing her husband’s body, Ivy wept bitterly and asked Dulang to find the murderer to avenge her husband. The beauty asked that, of course, Duro devoted himself to the investigation of the case. The police gathered up and down in the conference room to check the surveillance, and saw a video of Lin Mo entering and leaving the building. Sasha investigated and learned that private detective Gade had investigated and tracked writer Kunta. Following this clue, everyone subsequently locked Lin Mo. At this time, Lin Mo also came to Ivy’s flower shop following the business card and the perfume of the deceased, and saw Ivy. Seeing Ivy, Lin Mo suddenly felt helpless, or Ivy took the initiative to ask Lin Mo’s contact information. At night, Sasha and Wen Song came to Ivy’s flower shop and asked him about Lin Mo, but the other side denied that he had seen him.

At the invitation of Ivy, Lin Mo went to the flower shop to collect the perfume. But never thought that the other party knew that he had a keen sense of smell, and prepared a colorless and tasteless drug for him. After a long time, Lin Mo woke up and found himself tied to a chair by Ivy. Under the pressure of Ivy, Lin Mo finally stated his identity and the fact that he saw Kunta. While Ivy was out to greet guests, Lin Mo managed to get out of control. Lin Mo returned his teeth, tied Ivy to a chair, and went out to send away the guests. Just as he was about to close the door, An Qi suddenly appeared and pulled out a knife to stab Lin Mo. The blood splashed across the glass window, leaving a perfect arc, which reminded Lin Mo of the murder scene of Master and Kunta. It turned out that An Qi was the female killer “Sushi making machine”. She received the task, pretending to be a student approaching Lin Mo, and found a chance to kill it. In a critical moment, Ivy appeared and rescued Lin Mo.