On the 13th episode of "Ghost", there was a suspenseful searching for the spy that helps Cho Hyun Min(Um Ki Joon) in the department.

On this day, Kwak Hyuk Joo(Kwak Do Won) believed that Yeom Jae Hee received his jail meal that had some kind of drug in it. But he found out that the medicine that Yeom Jae Hee was taking for depression has been swapped out with other type of drugs.

Also, at the same time, Park Ki Young(So Ji Sub) and Yoo Kang Mi(Lee Yeon Hee) looked over at the CCTV shots to find out what happened before Yeom Jae Hee had died and solved the crime little by little.

Park Ki Young found out through this that the spy is someone that talked to Cho Hyun Min at 7:39 so he looked through the calling history. The result came out to be Kang Eung Jin(Baek Seung Hyun).

Not only this but also Kwak Hyuk Joo believed that Byun Sang Woo was the spy but he found that that he was with Kang Eung Jin on the day he visited Yeom Jae Hee in the jail. Then, he knew that Kang Eung Jin was in the center of everything.

Kwak Hyuk Joo and Park Ki Young went to capture Kang Eung Jin but Kang Eung Jin was on his way to delete every trace off of the USB.