Synopsis：Rumors spread that on the night when the new Imperial Palace in Luoyang was constructed, a divine dragon appeared, breathing fire and burning down the palace. The carpenters involved either died or went missing. Di Renjie was promoted unusually and appointed as the Deputy Minister of the Ministry of Justice to handle this "palace arson case." Throughout the investigation, he faced obstruction from mysterious forces and even survived an assassination attempt. However, the assassination incident provided him with a clue, and with the guidance of the hermit Mr. Li, he found the young master of the palace. Using the young master as a breakthrough point, he gradually uncovered the truth. With the help of his close confidante Liu Yueru, they successfully destroyed the hidden workshop in the underground palace where the young master produced his mechanisms. But the young master was merely a pawn, as behind him, there was a mysterious individual controlling the overall situation. At this moment, this enigmatic person was in control of the Thunder-Fire Mystical Dragon created using Lu Ban's craftsmanship, intending to wipe out Emperor Gaozong, Empress Wu Zetian, and all the civil and military officials in the palace, thus subverting the imperial court. Just as the situation reached a critical point, Di Renjie arrived, identified the weakness of the Thunder-Fire Mystical Dragon, and exposed the mysterious person, only to discover that this person was, in fact, a descendant of the hidden crown prince and the same Mr. Li who had once aided him.