Han Hae-Na (Park Gyu-Young) is a single woman and she teaches at a high school. She seems to have an ordinary life, but her family has a secret. Due to her ancestor's fault, Han Hae-Na's family has been cursed for generations. The curse causes her family, when they kiss someone, to turn into a dog at midnight for 6 hours. Afterwards, they revert back to their normal appearance. This transformation repeats itself every night until that person, in their dog appearance, kisses the same person.

Due to her family's curse, when Han Hae-Na meets a man for a potential romantic relationship, she asks that person to not kiss her. This usually leads the men to leave her. One night, Han Hae-Na, who is drunk, accidentally kisses Jin Seo-Won (Cha Eun-Woo). He is a teacher at the same high school, but they are not even close as colleagues. Han Hae-Na soon turns into panic mode and she keeps approaching Jin Seo-Won for a chance to have another kiss.

Meanwhile, Jin Seo-Won has a fear of dogs because of something that happened to him when he was young. He is a teacher with good looks and charisma. He is popular with the students.