During the Late Joseon Era, about the lives of four students at Sungkyunkwan University. We have Kim Yoon Hee (Park Min Young) who disguises as her brother in order to support her family.
She encounters Lee Sun Joon (Micky Yoochun) on one of her errands in order to take the tests for him except she got the wrong guy. Problems ensue and Lee Sun Joon applies her to SKK, an all boys school. With her stay at SKK, she meets the player, Goo Yong Ha (Song Joong Ki), and the badass, Moon Jae Shin (Yoo Ah In).
The four of them eventually form the historical F4 except none of the other 3 really knows that Yoon Hee is a girl.
