Set in late Joseon-era Korea, the film follows Lady Cho, a sharp-tongued noblewoman trapped in a loveless marriage. Publicly, she is the model of virtue. Privately, she is bored, bitter, and dangerous.
Lady Cho’s husband plans to take a young girl as a concubine. Jealous and resentful, Lady Cho asks her cousin Jo-won, a notorious aristocratic womanizer, to secretly seduce her first, ruining her purity before the marriage can be completed.
Jo-won agrees, but instead proposes a more ambitious wager. He challenges Lady Cho: he will seduce Lady Jeong, a respected Catholic widow famous for her chastity and moral integrity. If he succeeds, Lady Cho will sleep with him. If he fails, he will give up worldly life and become a monk. Lady Cho accepts.
Jo-won proceeds with both schemes. He sexually exploits the to-be concubine, who is young, inexperienced, and emotionally vulnerable. Meanwhile, he carefully engineers encounters with Lady Jeong, presenting himself as sincere, respectful, and emotionally devoted. Over time, Lady Jeong develops genuine feelings for him, believing his love to be real.
During this process, Jo-won himself begins to fall in love with Lady Jeong, despite originally viewing her only as a conquest. However, Lady Cho continues manipulating events from behind the scenes. She toys with Kwon In-ho, a young scholar who loves the to-be concubine, deceiving him with forged letters and false hopes.
Eventually, Kwon In-ho discovers Jo-won’s affair with Lady Jeong and exposes it. Jo-won is attacked by Lady Jeong’s family and dies from his injuries, never able to confess that his feelings for her had become sincere.
After Jo-won’s death, Lady Cho reveals the truth of the wager to Lady Jeong, cruelly informing her that she was never loved, only used. Lady Jeong is devastated and retreats into religious life. Lady Cho, having “won” the game, remains outwardly composed but emotionally hollow.
