The story follows an unexpected soul swap between a prince who has forgotten how to smile and a wandering merchant who has forgotten her past.
Crown Prince Yi Gang of Joseon has lived in grief and bitterness ever since the death of his crown princess. Abandoning all personal joy, he devotes himself entirely to a long-prepared plan for revenge. Just as that plan finally begins to unfold, he encounters Park Dal I, a traveling merchant who astonishingly resembles his late wife.
In a twist of fate, Yi Gang and Dal I suddenly exchange bodies for reasons neither understands, plunging them into escalating confusion and turmoil.