Seong-ae, who was innocent as a child, had her first relationship with Geon-woo, who was a jobless gangster in the neighborhood. Seong-ae, who was curious, opened her eyes to sex after having a relationship with her brother. As an adult, Seong-ae looks ordinary and plain on the outside, but perhaps because of her experience with her first man, her sex has become rougher since then. During her school days, she was tricked by her best friend, Yoo-ri, into stealing Geon-woo, and eventually, the two are now married. However, Geon-woo still meets Seong-ae from time to time secretly without Yoo-ri's knowledge and enjoys sex. Meanwhile, Yoo-ri also enjoys secret sex without her husband's knowledge with Myeong-jin, a junior at Geon-woo's company. Later on, Yoo-ri becomes tired of Myeong-jin, introduces him to Seong-ae as patronage, and tells them to enjoy sex. Seong-ae, who knows but is deceived, begins to expose the relationship between Gun-woo and Yoo-ri to the world.