Jung Wan, Sun Mi, and Ji Hyun were high school classmates. It's been 20 years since graduation and as they turn 39, the three friends are leading completely different lives, although they are as close as sisters. Jung Wan was the first to get married but is now divorced, while Sun Mi chose a career over marriage and is now a successful interior designer, but is desperately lonely. Ji Hyun married a successful businessman and seems to be a good wife and mother, but feels like she is dying inside. What happens when love comes knocking on their doors once again? Jung Wan tries to throw herself into work to forget her ex but meets a new man. Sun Mi is desperate to get married before she turns 40. Ji Hyun, tired of her dull marriage, reunites with her first love who tempts her heart once more. Love has come once again to these three women in their late 30s. Can they fall in love again?