When her longtime crush starts dating someone else, Hee-won drowns her sorrows and has a passionate one-night stand. Soon after, she finds out that she's pregnant, and that the father is Doo-joon, the board chairman of the high school she teaches at! Determined to do the right thing, the principled chairman proposes on the spot. Though complete strangers outside the bedroom, Hee-won gets swept into a whirlwind engagement. Can this accidental couple turn a scandal into true love?