Crown Prince Sado secretly retreats to a hidden palace garden to read foreign books and the mystical Scripture of the Jade Pivot. When King Yeongjo discovers the book, he accuses Sado of attempting to kill him the previous night. Witnesses confirm the attack, and Yeongjo orders his son to be confined inside a rice chest.

Despairing within the chest, Sado tears a page from the scripture. It opens a passage through time and brings him face to face with Yi Geum, a young Joseon prince. Sado recognizes the name as Yeongjo’s birth name but initially fails to understand that the frightened boy before him is his father’s younger self. Yi Geum longs for the protection of his older brother, and Sado comforts him.

Each page Sado tears reveals Yi Geum at another stage of life: first as an insecure prince, then as crown prince, and finally as a king suspected of poisoning his brother. In every encounter, Yi Geum confesses his fear of rejection, power, and abandonment. Sado offers him the affection and reassurance that he himself never received from Yeongjo.

Meanwhile, Sado grows weaker and remembers the night he raised a sword against his father. The attack was real, and too many people witnessed it for the king to ignore. When Yi Geum finally appears as Yeongjo, Sado understands that he has been speaking to his father across time.

Yeongjo tells Sado that after the attempted attack, father and son can no longer remain alive together. He offers Sado the chance to kill him, but Sado instead collapses and asks his father’s forgiveness. Sado dies inside the rice chest, leaving behind the young son who will eventually become King Jeongjo.