As the Tang dynasty approaches its 689th year, the rise of Wu Zetian to the throne generates fierce opposition from the imperial court. Amid this turbulent backdrop, a Guan Yin statue, overlooking the great Luoyang palace, unexpectedly bursts into flames—an ominous signal that sets the stage for a series of horrific events. Pei Donglai, a dedicated penal officer, along with his superior, embarks on a mission to investigate this strange fire, only to find their efforts abruptly halted by a subsequent, mysterious blaze that tragically claims the life of their own superior.
In light of these unsettling developments, Wu Zetian commands the release of Di Renjie, a seasoned detective who has turned against the establishment. The solemn announcement from the Imperial Abbot declaring that Di's exceptional skills are crucial to uncovering the truth behind the fires becomes the reason for his reinstatement as the royal detective. Jing'er, Wu's loyal attendant, is entrusted with the task of bringing Di from his confinement and subsequently assisting him in his investigation. Their adventure ignites with intensity as Di encounters a field of assassins right at the prison gates. Wu's determination to reestablish Di's position is juxtaposed with her expectation for Jing'er to watch over him closely—creating a fraught landscape of loyalty and subterfuge.
As Di delves deeper into this intricate web of mystery, he reconnects with Shatuo, an old acquaintance whose cryptic messages guide him toward Donkey Wang, an elusive figure ensconced within the winding paths of the Phantom Bazaar. When Pei attempts to arrest Shatuo for withholding vital information, Di intervenes just in time. Together with Pei and Jing'er, Di ventures into the shadows of the bazaar to confront Dr. Wang, only to be ambushed by someone posing as the Imperial Abbot. Following a fierce confrontation, Pei pursues the impersonator to a secretive location, revealing a complex network of deception and malice.
In a twist of fate, Prince Li's unexpected present of Di's long-lost mace surfaces as a vivid reminder of the challenges awaiting him. While Di pledges to remain politically neutral, Prince Li falls victim to a deadly plot devised by unknown adversaries. With suspicions pointing towards the Abbot, Wu issues a grim ultimatum: any effort by Di to probe into the monastery may result in his own death. Meanwhile, Pei discovers significant information within the inspector's records and quickly departs with the critical documents, tragically falling into a dark scheme.
Arriving at the monastery, Di uncovers a shocking revelation; the Imperial Abbot is revealed to be none other than Jing'er, who has skillfully mastered the technique of disguise using acupoints. This discovery ignites a sequence of events, leading Di to theorize that the Empress may have covertly manipulated the Abbot to reinforce her tyrannical authority and neutralize any threats, including the former Emperor. As Jing'er seeks to confront Di, she inadvertently finds herself caught in a deadly snare set by assassins, meeting her tragic end in the hold of the Empress.
Amid the chaos, Di stumbles upon Pei, only to find that he has succumbed to the debilitating venom of the fire beetle. In his final breath, Pei passes to Di the incriminating diagrams that implicate Shatuo in an evil conspiracy aimed at toppling the Empress and wreaking havoc across the city.
Confrontal that moment at the Buddha statue, the treacherous Shatuo reveals his plans to avenge himself on the palace by orchestrating a catastrophic downfall of the statue. He has already eliminated key officials who attempted to thwart his plots, including Prince Li, whose existence posed a threat to his ambitions. With Shatuo seizing power under Prince Li’s authority, he mobilizes his forces to brutally retaliate against Wu if she survives.
During a gripping showdown, Di finds himself entangled in a struggle against Shatuo, enduring the effects of fire beetle poison. Yet, he perseveres, skillfully redirecting the statue's fall and leaving Shatuo to perish beneath the relentless blaze of the sun.
In the aftermath of this tumultuous battle, Di heroically saves Wu from imminent danger posed by the collapsing statue and warns her of the looming threat from the rebel army. Chastened by these harrowing events, the Empress vows to govern with fairness and reinstate stability to the Tang dynasty when her reign concludes. Rejecting Wu’s invitation to join her court, Di chooses to resign as the inspector, retreating to the enigmatic Phantom Bazaar alongside Dr. Wang, where he must contend with the grim realities surrounding his condition.
