Three years ago, Su Ming was just the most inconspicuous idle prince in the capital, obsessed with the abandoned royal hunting garden on the outskirts of the city all day long. No one knows what kind of secrets are hidden in that desolate land - thirty meters underground is the perfect underground kingdom he spent three years building.
When everyone thought he was the most harmless dude, a conspiracy against the Su family quietly unfolded. Li Tingyu, the second son of the prime minister, led the imperial army to search the Su mansion on the grounds that he found out that the Su family had hidden weapons. But Su Ming smiled and used his plan to lead Li Tingyu to the secret base. When the Imperial Army discovered hidden evidence of rebellion underground, Su Ming turned the evidence back to ironclad evidence that Li Tingyu had colluded with his relatives.
Overnight, everyone in the Li family was slaughtered, and Su Ming was named the "Zhongyonghou" and took charge of the capital's imperial army. But a bigger mystery then surfaced - there was actually a secret passage connected to the palace hidden underground in the seemingly ordinary hunting garden. The emperor summoned him late at night and handed him half a dragon-patterned jade pendant: "Xiaojiu, help me find out the truth about the palace incident twenty years ago."
On the surface, it is a battle for power in the palace, but behind the scenes, it is a contest between the underground kingdoms. As Su Ming's secret base continues to expand, what is connected to it is not only the fate of the capital, but also the earth-shattering change that has been sealed in the dust.
