Poor law school student, Jeonghun Han, experiences a time slip via the time roulette machine he accidentally finds at his father's place. When he comes to his senses, he finds himself on a battlefield during the Joseon dynasty! But before Jeonghun can even process what’s happened, he’s approached by a messenger named Jun, who informs him that he can only go back to his time by completing the time roulette’s mission. Will Jeonghun be able to complete his mission and return to his time?