
The rest is that they go investigate the fake delivery man's apartment cause he's a suspect of killing the rooftop guy and they find him dead in his bathtub apparently by suicide and close the case as murder followed by suicide out of guilt. Forensics guy doesn't buy it cause these 2 were friends in highschool and gets suspicious but peng yanqing tells him to forget about it

Then some people related to drugs start dying with notes near the body with riddles written in them serial killer style and one of the victims is a member of the yakuza. Gang blondie goes to peng yanqing and tells him to investigate this murder cause he's suspicious the killer is a traitor from inside the yakuza
In the past:
· Family of 4 is murdered and their 14 yo son goes missing (implied to be yi fu). Last person that saw them was a criminal pretending to be a delivery man, he's probably the killer but they didn't have enough evidence to arrest him.
· Yi fu was kidnapped as a kid and got hit in the head prob causing him to go insane (lol) and made him kill 2 people.
Present day:
· A man was murdered with a stab wound in his throat and acid was thrown on his face making him indistinguishable plus he fell down the rooftop while bleeding from the stab wound. There's a card in his pocket that belongs to a science company of some sort that yi fu works at and peng yanqing goes there to investigate, comes across yi fu and brings him for interrogation. He's suspicious cause his alibi is being in his office but the security footage of his office has been tempered with and he has calluses in his hand that implies knife training despite denying practicing any sort of martial arts (rooftop guy was killed with a stab wound from a tactic knife, not a kitchen knife). Peng yanqing knows it was him but can't prove it