Im Jung-hwan is a playboy who is still in college after nine years, chasing after girls and never wanting to graduate. Go Eun-joo, a prosecutor who is tough as nails, is a bomb that no man would want to go out with. One day, she meets this hopeless playboy student Im and falls madly in love with him. After days and days of her persistent seduction, IM becomes a father of twins after a one-night stand. Finally, they get married. But even under these circumstances, nothing could change the nature of this 'natural born playboy' and he keeps committing adultery. Thus Eun-joo's 'husband taming project' begins.