Yoon Sang Hyun worked to find Kap Dong himself and pretended to be Kap Dong.
On the 5th episode of tvN "Kap Dong" broadcast on May 2nd, Ha Moo Yeom (played by Yoon Sang Hyun) told Yang Chul Gon (played by Sung Dong Il) that he was a Kap Dong and started to confess.
On this episode, Chul Gon was confused because of Moo Yeon who confessed that he was Kap Dong. At this time, Moo Yeom hurt Chul GOn's pride saying, "I said I'd let you go and now your'e confused because I'm saying that I'm Kap Dong, right?"
Oh Maria (played by Kim Min Jung) who learns of this truth came to Chul Gon and said that Moo Yeom had made a false confession. Maria explained, "This is to be Kap Dong to find the real Kap Dong."
Moo Yeom's father was pushed to be the suspect in the serial murder that happened seventeen years ago and was tortured and died. Afterwareds, Moo Yeom wanted to resolve his father's revenge and worked hard to find Kap Dong.