Six years ago a mysterious shooting takes place in Seoul. The after effects of the shooting results in Han-kyu Lee (Song Kang-Ho) losing his job at the NIS (National Intelligence Service). Six years later, Ji-won Song (Kang Dong-Won), an ex North Korean spy. now operates somewhere in the Seoul metropolitan area. As these two men hide their identities and work their particular angles, trouble brews again ....

After being dumped by her boyfriend just before their 100 day anniversary, Ha-Young, meets a college guy named Hyung-Joon when she accidentally kicks a can that hits him in the face and causes him to scratch his Lexus. He demands she pay him $3000 on the spot. She escapes from him, leaving her wallet behind.Hyung-Joon stalks her, demanding money to pay for his car. Since she is a poor high school student Hyung-Joon writes up a "Enslavement Agreement" for Ha-Young in order to pay for the damage to his car. Ha-Young is thrown into a nightmarish slave life for 100 days, cleaning his house, running his errands, doing his homework and cleaning his car.By accident she finds out that the damage to Hyung-Joon's car only costs $10! She then takes her revenge. However, before she knows it Hyung-Joon shows up at her house as her new tutor! He once again takes advantage of her, but soon Ha-Young finds herself falling head over heels for Hyung-Joon.