The story is about a bright and innocent 27 years old guy (Yoo Gun) with an IQ of 65, who is neglected by society because of his problems, but fights hard to overcome them. Seo Eun-Hye (Kim Ok Bin), a a fumbling swindler is a woman who thinks love is nothing more than sadness and difficulties piling up one after another... until our "Forrest Gump" shows up and turns her life upside down.

Lee Jung-Hyun (Go Su) is accused for murdering Oh Soo-Ah's (Lee Da Hae) father. He runs away and becomes a fugitive. Later, he returns and seeks out revenge. Oh Soo-Ah who is the successor of the enterprise "First Electronic" falls in love with Lee Jung-Hyun.

Chuno follows the story of a runaway slave in Joseon times and the slave hunter who pursues him, with a woman who completes the love triangle.