Secrets of Lee Seung Gi, Lee Hee Joon, Park Ju Hyun, and Kyung Soo Jin started to unfold in the least possible way they expected.

Police officer Jung Ba Reum tries his best to search for the answer why he has been experiencing a sudden change of behavior.

Lee Seung Gi is Determined to Know the Truth

In search of the truth, Jung Ba Reum (Lee Seung Gi) is slowly finally getting the answer to all his questions. He visited the room in the investigatory department where all the evidence from the past is piled up.

The police officer started to look for the same marks that the murderer did to all his victims before. The headhunter's secret is engraved on the victims' fingers, indicating the gender and subject order.

Another hint that Jung Ba Reum discovered was that the hole in the finger of the victims was the same in the ear of a mouse that has been tested on animals. He still can't believe that the sudden change in his sensitive olfactory angle was due to the surgery he had back then.

He visited Han Seo Jun (Ahn Jae Wook) and asked about the possibility that the serial killer's brain can be put into someone else's brain and turn into a murderer.

In this episode, it has also been revealed the past failed surgery Han Seo Jun had years ago, in which he used his friend David Lee (Jo Jae Yun) to cover up his mistakes. David Lee ended up being expelled from the hospital for something he never committed.

After knowing Han Seo Jun's side, Jung Ba Reum went to Jung Ae Ri (Choi Yung Shin) and listened to everything she said. He found out that the doctor who performed the surgery on him was Han Seo Jun.

He couldn't believe what he just heard as this poses a possibility he tends to become a psychopath because of Han Seo Jun.

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Choi Hong Ju Gave Birth to a Psychopath

Meanwhile, it was revealed before that even before Sung Yo Han (Kwon Hwa Woon) was killed, Choi Hong Ju (Kyung Soo Jin) was pregnant with their first child. But knowing that her boyfriend is a serial killer, she wanted to abort the baby.

It was revealed in episode 9 that Choi Hong Ju did not proceed with the abortion and raised the child alone instead. She knew from the start that her children could have the possibility to become killers too.

On the other side, detective Go Mu Chi (Lee Hee Joon) was arrested for killing Woon Jae Pil (Jung Suk Yong). Jung Ba Reum found out the true culprit by checking the CCTV inside the hospital. He immediately left after watching the footage and said he knows who the real killer is.

ALSO READ: Lee Seung Gi's Suspense Drama 'Mouse' Keeps Achieving New High Viewership Ratings

Afterward, Jung Ba Reum and Lee Hee Joon talked about the crime. The two felt the same anger, until unconsciously, Jung Ba Reum found himself turning into a monster in front of his friend and colleague.

This scenario supports the suspicion that Jung Ba Reum can turn into a psychopath.

Watch the teaser below to know what to look forward to in the upcoming episode 10 of "Mouse"!

Have you watched "Mouse" episode 9? What are your thoughts about it? Tell us in the comments section below!

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Written by Shai Collins