Yook Dong Shik (Yoon Shi Yoon) is a timid clerk at a brokerage company, who witnesses a murder and happens to find the killer's diary. While fleeing the scene, he is struck by Police Officer Shim Bo Kyung's (Jung In Sun) car and loses his memory. With the incriminating diary in his possession, he mistakenly comes to believe that he is the serial killer himself.
(Source: DramaWiki)