Kim Jinwoo, who is studying at a college prep academy, begins to notice something strange about the outfit of his married math teacher. She teaches with a blank expression and without wearing underwear, and Jinwoo finds his eyes increasingly drawn to her. Meanwhile, Jeong Sua, an unmarried young teacher at the same academy, approaches Jinwoo playfully… but with clear intentions. What’s hotter than the air inside the academy is the desire flowing between the three of them.