Ji-hyeon and Min-soo are a younger couple who just got married and started a family. For Ji-hyeon, Min-soo is a perfect husband without shortcomings, but the only downside is that she is not satisfied with her younger husband's sexual life due to her strong sexual desire. Then one day, Ji-hyeon, who accidentally placed an order through a delivery app, found out about a delivery man named Dong-hoon who came to their home to drink a glass of water, and then she finally crossed the line. Ji-hyeon, who has tasted the thrill that she has never felt from Min-soo, visits Dong-hoon every night, and her husband Min-soo spends each day with her without knowing this... The love game between a man and a woman, who cannot be seen at all, is just beginning.