Jang Yeong-sil, a genius scientist, rises from slavery to the rank of jong sam pum (Senior Third Rank) thanks to King Sejong's favor, but after the palanquin incident of 1442, he disappears completely from historical records. Where did he go? In 20th-century London, a painting by Rubens titled "Man in Hanbok" appears in an auction at Christie's. The identity of this unknown Asian figure painted by Rubens traces back to the era of King Sejong in the 15th century. Though born a slave, Jang Yeong-sil possessed exceptional brilliance. However, he receives an order from Ming China demanding that he be executed or handed over to them. With King Sejong's help, he escapes by joining the Ming explorer Admiral Zheng He on a voyage to Europe and even meets the Pope in Italy. But Jang's belief that the world is round is deemed heretical, and the Pope orders his execution. Fleeing for his life, Jang reaches Florence alone, where he encounters a seven-year-old Leonardo da Vinci.