Synopsis：When the newly built imperial palace in Luoyang was supposedly visited by a divine dragon that spat fire and burned it down, the carpenters working there were either killed or went missing. Di Renjie was unexpectedly promoted to the position of Deputy Chief Minister of the Dali Temple to investigate the "Palace Arson Case." Throughout the investigation, he faced persistent obstruction from a mysterious force, even surviving an assassination attempt. However, the assassination attempt led him to crucial clues, and with guidance from a reclusive scholar named Mr. Li, he tracked down Master Gong. Using Master Gong as a breakthrough, Di Renjie gradually uncovered the truth. With the help of his confidante Liu Yueru, he successfully destroyed Master Gong's trap-making base hidden in an underground palace. But Master Gong was merely a pawn; behind him, a mysterious mastermind was orchestrating everything. This mastermind had created a "Leihuo Xuánlóng" (Thunderfire Mystic Dragon) using the legendary carpentry skills of Lu Ban, intending to destroy the palace during an imperial gathering, killing Emperor Gaozong, Empress Wu, and all the officials—thus overthrowing the court. Di Renjie arrived at the critical moment, identified the weakness of the Leihuo Xuánlóng, and exposed the mastermind, who turned out to be a descendant of the deposed crown prince—none other than the Mr. Li who had previously helped him.