Choi Sang-eun somehow ends up with the best qualifications for marriage and decides to start a business out of this. She becomes a contract marriage master who works with countless singles who need to get married by going through weddings and even registering their marriages if needed. Over 13 years, she has married and divorced 12 times, but because of the side effects that happen within and outside of the business, she decides to retire and is letting her clients go one by one. While Jung Ji-ho, the mysterious long-term client she's been seeing every Monday, Wednesday, and Friday for the past five years, is on her mind, Kang Hae-jin, a former K-pop idol and superstar actor, moves upstairs and signs a contract with her for Tuesdays, Thursdays, and Saturdays, and the three get entangled in an every-other-day romance.