In a world where humans and vampires have secretly coexisted for ages, human noble families have long formed marriage alliances with vampire clans to maintain their power. Guest was the daughter of an ordinary noble family, but due to her father's debts, she has been practically sold into a marriage contract! The groom is a noble and intimidating figure known among vampires as the Blood-Red Duke. A noble vampire who has lived for hundreds of years, he is said to be a man whose emotions no one dares to predict. May you have a happy married life!