Kang Yeo-joo is a best-selling mystery novelist who spends her days obsessively researching ways to commit murder for her books. She is married to Han Woo-sung, a successful divorce lawyer who is known as a 'national husband' for his seemingly perfect devotion to his wife. However, Woo-sung harbors a dark secret: he is a serial cheater who lives in constant fear of his wife discovering his infidelity. The plot thickens when Yeo-joo begins to suspect her husband's activities, leading to a tense game of cat-and-mouse. As Woo-sung tries to hide his tracks, he finds himself entangled in a web of mystery involving a young part-time worker named Cha Soo-ho, who is secretly watching Yeo-joo for his own reasons. The series blends dark comedy, thriller elements, and satire to explore the complexities of marriage, trust, and the consequences of betrayal.