A teacher is irritated by a busybody student until he learns about her past. Hye Na is an outgoing, bubbly student who becomes a thorn in the side of Jun Hyoung, a teacher. Hye Na's unrestrained and free-spirited behavior soon begins to interfere with Jun Hyoung's life, but his mentor forces him to watch out for the meddlesome girl. But will his attitude change when he discovers Hye Na's secrets? "You Know What? It's a Secret" is a 1990 South Korean film directed by Jo Keum Hwan.