Ánh Dương is a beautiful, well-educated girl, pursued by many boys. One day, Ánh Dương received a gift box with a love letter from a mysterious, unnamed boy. Who is that person? Is it a close friend Thiên Minh or basketball hotboy Hoàng Phong, cool singer Hải Dương or good classmate Tuấn Anh - who specializes in helping Ánh Dương in class? "Who is one of the 4 boys, who sent the letter and the gift?" that is the question Ánh Dương and her bestfriend Gia Nghi must find out before finishing their final year at this high school.