A murder mystery crosses the time-space continuum from the Chosun Dynasty to modern-day Seoul. Crown Prince Lee Gak (Park Yoochun) and his three men from the Chosun Dynasty are transported 300 years into the future to 21st-century Seoul after the mysterious death of his wife, the Crown Princess. They literally fall into the rooftop home of Bak Ha (Han Ji Min), who reluctantly takes charge of the group of misfits. When Gak meets Ha’s stepsister, Hong Se Na, he is stunned to find that Se Na bears a striking resemblance to his dead wife and is determined to solve the mystery of her death. With his own resemblance to the CEO’s grandson at the company where Se Na works, Gak assumes the identity of the young man, Tae Yong, to be close to her. Meanwhile, Tae Yong’s cousin, Tae Moo, returns from New York to report that his cousin is missing but is shocked to learn of Tae Yong’s return to the company. Will the Crown Prince be able to solve a 300-year-old mystery and return to his rightful time period?