The whole school is convinced Xu Zhun is sick: every day, he talks to an empty seat and serves food to someone. Only he knows there's really something sitting there. He's the only person on Earth who can see Elementals, strange beings formed from chemical elements and hidden among humanity.
King Ping is about to settle accounts with Earth. Twenty-two Descendants have been reborn and scattered across the world, and the Orderly Clan has arrived to find them. Meanwhile, an old case involving a nitrogen-based medicine that evaporated and a wrongfully accused teenage inventor forced into exile remains unresolved.
After seventeen years of being a coward, Xu Zhun is pushed into finding them all. But the more he finds, the more uneasy he becomes. Why is he the only one who can see them? And who switched the bottle of Seven-Two Transformation Potion?