Gyeong-soo and Jeong-min used to be the happiest couple in the world. However, Jeong-min is left home alone after her husband leaves to the regional area for a lengthy business trip. While she tries to deal with her lonely feelings, her son’s tutor Min-hyeok starts flirting with her hard. And although Jeong-min knows she shouldn’t, she starts being attracted to Min-hyeok more and more. Meanwhile, Gyeong-soo finds his place in a boarding house in the regional district and starts getting attracted to the owner of the board house, who is a single mother with a young daughter.

Young and beautiful woman, Shin-hye, she is a good housewife with all of her focus on her husband and housekeeping. However, she has a concern these days. She and her husband are drifting apart from each other, while her husband has been refusing sex with her and treating her like a ghost. As her unhappiness with her husband is growing bigger, she attends her high school alumni meeting, where she encounters her first love, Seong-jin. Shin-hye is drawn to Seong-jin, who is a cool handsome grown-up man now. She slowly steps into the forbidden realm, as to say ‘affair’ in spite of herself.

"Trust me tonight" Min-ho is preparing to get a job and is spending some time in his parents' house. However, his parents aren't home and only his young sister-in-law is there. His brother Hyeon-soo had left the house after fighting with his wife. Min-ho can't help but feel attracted towards his young and appealing sister-in-law.