Woo Jin and Samuel are a sexless couple. After being married for a long time, the days of passion are long gone. One day, Samuel finds out his friend, Jung Soo, is having an affair. Woo Jin insists on telling Se Yeon about the truth.
As life hits them hard, Samuel and Woo Jin decide to work together and blacklist the couples who are cheating on their partners for money. Woo Jin finds targets from the hotel she is working at, and Samuel puts a tail on them.
Samuel and Woo Jin look for another target. An old man comes to Woo Jin's hotel, and it seems like he's having an affair. Samuel and Woo Jin follow the couple to the mountains and the sea to gather evidence to blackmail the couple.
A couple gets into Samuel's taxi, and it seems like they are having an affair. Samuel and Woo Jin try to make an effort for their relationship as they see the passionate adultery couple.
Woo Jin goes to the hospital, and Samuel is not in the bed. He is with Min Soo, his neighbor and also his cleaning mate, in the past. Woo Jin calls him and catches him lying. She decides to tail him to see what is going on.
Feeling betrayed, Woo Jin decides to blackmail the woman next door. Woo Jin questions Samuel, and Samuel tells her a secret he has been keeping. Woo Jin is flustered, and it becomes a huge fight. What will be the end of this couple?
