Seo Yi-soo, a young prosecutor, is faced with a distressing situation when her journalist sister mysteriously disappears. While delving into the clues left behind by her sister, she stumbles upon a shocking revelation involving the country’s largest law firm, Yoon & Kang. In her quest for information, Yi-soo approaches Yoon Hyun-seong, her senior from college and the son of Yoon & Kang’s representative, proposing a contract engagement. Aware of his legal expertise, she suggests a one-year engagement contract. Their relationship begins as a mere arrangement to fulfill their individual objectives. Yi-soo, without harboring any doubts, firmly believes in this pragmatic alliance. However, her unwavering faith is shattered in an instant. As she rejoices momentarily, fate throws an unexpected twist at her. The air fills with a captivating blend of wood and cigarette smoke. Hyun-seong, with a cigarette poised between his index and middle fingers, invites her to experience it. His lips gently graze the cigarette, revealing a lazy yet alluring smile. His eyes exude indifference, while the veins on his hand appear prominently. As the tip of the cigarette turns red, Yi-soo’s heart races, feeling as if it were shattered into pieces.