Red Swan tells the story of Oh Wan-soo, a woman born into a poor family, who turns her life around and becomes a world-class golfer, catching the attention of many, including her future husband, Kim Yong-kook, the heir to the Hwain Group. Struggling to pay off her mother's debts, Wan-soo agrees to marry Yong-kook, but soon becomes unhappy when she finds out about her husband's affair. For over a decade, she lives with her husband and is determined to make it work, but things begin to change quickly when she faces the biggest night of her life.