Han Hae Na is a single high school teacher with a family secret. Because of an ancestor, Han Hae Na’s family has been cursed for generations. Whenever a member of her family kisses someone, they turn into a dog at midnight for six hours. Afterward, they return to their normal appearance. This transformation repeats every night until that person, in their dog form, kisses the same person. Whenever Han Hae Na meets a man with whom she might start a romantic relationship, she asks him not to kiss her. This usually leads the men to break up with her. One evening, while drunk, Han Hae Na accidentally kisses Jin Seo Won, a teacher at the same high school—even though they aren’t even close as colleagues. Han Hae Na immediately panics and persistently pursues Seo Won for a chance at another kiss. However, Jin Seo Won is afraid of dogs.