Inspired by Mark Twain's 1881 novel The Prince and the Pauper, the film is set in the Joseon Dynasty with Ju playing the dual role of a king and a beggar.

While to future generations King Sejong would stand as a legendary figure for his creation of the Korean alphabet and advancing the country’s scientific research and law, as Prince Choong-nyung he was known to be a bit of a reclusive bookworm.

The prince, who strongly refuses to become the king and just wants to live a happy and stress-free life buried in his books, chooses to escape the palace before his coronation ceremony.

There he runs into a bad-tempered drunken slave named Deok-chil, who happens to be at the palace to save the love of his life who was captured by government officials and put in prison for being the daughter of a suspected spy.

As Choong-nyung ventures outside the palace walls, he begins to open his eyes to the people living in extreme poverty and experiences the life of the common man.