"Duel" has a knack for providing answers only to raise more questions. Episode four is all about tracking down Choi Joo-sik, the subject of the 1993 experiments before Seong-hoon can get to him. Deuk-cheon's friends and the prosecution team keep dancing around each other as our two heroes get ready to infiltrate enemy lines. Mi-rae joins the game as shocking truths come to light.
The deeper we go into the clone business the more confusing it gets. On one hand, I was right about Jeon Byeong-joon (Jo Jae-ryong) looking a lot younger than his current styling in Seong-joon's (Yang Se-jong) flashbacks. It seems that a young man in 1993, when Choi Joo-sik (Jo Jae-wan) was experimented on was killed by him and Jeon. Was the young man a scientist killed as revenge for his twisted experiments?