When Crown Prince Lee Gak is transported 300 years into the future to present day Seoul along with his three retainers, they believe that it is their duty to solve the murder case of the Crown Princess in order to return to Joseon.
They land in the rooftop apartment of Park Ha, a cheerful woman in her mid-20s, who eventually believes the odd quartet's predicament and becomes their guardian.
As Park Ha educates the four on life in the 21st century, Lee Gak comes across Hong Se Na, who seems to be the reincarnation of his wife.
Taking on the identity of Yong Tae Yong, Lee Gak slowly begins to unravel the murder of Yong Tae Yong and in turn moves closer to solving the murder case of the Crown Princess.
As he finds himself in love with Park Ha, he figures that maybe the Crown Princess was not so perfect after all...
'Even after three hundred years has passed, I'll still love you.' - Rooftop Prince