Kyung-min lives alone in a one-room apartment. One day, she finds traces of a stranger breaking into her room and soon a mysterious murder case begins to unravel.

In the era of 7.2 million baby boomers, nine female high school alumni from 1958, Year of the Dog, have lived different lives for 40 years after their high school graduation. After 40 years, they meet at a girls’ high school reunion to realize their dreams, and to fulfill those that they have not achieved.