"Gentleman's Dignity" depicts the romantic relationship between Kim Do-Jin (Jang Dong Gun), an architect with a scathing tongue, and strict high school teacher Seo Yi-Soo (Kim Ha Neul), who moonlights as an umpire at amateur baseball games.

Kim Do-Jin (Jang Dong Gun), Im Tae-San (Kim Su-Ro), Choi Yoon (Kim Min Jong) and Lee Jung-Rok (Lee Jong Hyuk) are four 40-year-old men, who have been friends since they were teenagers. Kim Do-Jin and Im Tae-San run a successful architecture company. Kim Do-Jin is brutally honest, confident and loves his work, but because of his personality is still single.

One day, while waiting for someone, he spots a woman standing outside the cafe. Kim Do-Jin feels something for her on first sight. The woman's name is Seo Yi-Soo (Kim Ha Neul). She is a high school teacher and umpires amateur baseball games in her free time. The next moment, Seo Yi-Soo is gone.

On a sunny afternoon, Kim Do-Jin walks along the street. He bumps into a woman and a thread on her knitted skirt becomes stuck to his baf. The woman is the same woman Kim Do-Jin saw outside of the cafe. Seo Yi-Soo doesn't realize her skirt is being becoming unravelled until a large portion of skirt becomes undone. Seo Yi-Soo is now extremely embarrassed and quickly hops into a taxi cab. Before Kim Do-Jin can get her phone number, she is gone.

One evening, Kim Do-Jin goes out to buy something from the market. Two young men stop Kim Do-Jin and attempt to intimidate him into giving them money. At that time, Kim Do-Jin's friend Choi Yoon shows up and they all get into a fight. Later at the police station, Kim Do-Jin refuses to forgive the kids, which means the kids will get prosecuted. Meanwhile, Seo Yi-Soo receives a phone call from the police station that some of her students have gotten into trouble. Kim Do-Jin and Seo Yi-Soo cross paths again, but he leaves while she enters the police station. Seo Yi-Soo gets the victims phone number from the police officer and keeps leaving messages on is cellphone. She doesn't realize the victim is Kim Do-Jin.

The following day, Seo Yi-Soo umpires a baseball game among some friends. Those friends include Kim Do-Jin and his pals. After the game, Kim Do-Jin asks her if she recognizes him, but Seo Yi-Soo pretends she doesn't because she is still embarrassed about the skirt incident.

Finally, Seo Yi-Soo figures out that Kim Do-Jin is the man that was victimized by her students. She goes to see Kim Do-Jin at his office. There, Kim Do-Jin figures out that Seo Yi-Soo is in love with his good friend and business partner Im Tae-San, but his business partner is in love with Hong Se-Ra (Yoon Se-Ah) ... who is Seo Yi-Soo's best friend.