This Five Thunder Temple is far too dangerous.
Only now did Hou Junji fully understand why this place had earned a personal inscription from His Majesty—and why all sources of fire were so strictly controlled.
He glanced again at the storerooms piled high with alchemical materials, then at the thick smoke still swirling behind the main hall.
Without hesitation, Hou Junji turned on his heel and left, making a firm decision in his heart: he would never come back here again.
Watching the Daoists—faces lit with excitement—as they ran headlong toward the smoke, Hou Junji felt an unexpected trace of admiration.
Where did General Yaoshi even find a group of death-defying lunatics like this?
Only after striding out through the temple gates did Hou Junji finally let out the breath he'd been holding.
Li Jing and Li Shiji were not here.
And that, paradoxically, made things worse.
Then… who else among the Ganlu Hall inner circle could he seek out?
As he walked, Hou Junji reviewed the situation in his mind.
Wei Zheng was definitely not an option. After the New Year court assembly, Wei Zheng—like Hou Junji himself—had been sent out on imperial business.
Hou Junji's task was intelligence gathering, plain and simple: preparation for the next campaign to destroy a state.
Wei Zheng's mission, however, was far heavier.
At the New Year Grand Assembly, the Ministry of Revenue had reported that after the annihilation of the Eastern Turks, more than a million people—Han and Hu combined—had crossed the borders to submit to Tang.
Where to settle them, how to make them self-sufficient, whether to establish new prefectures and counties—plans for all of this had already been drafted at the New Year, and Wei Zheng had been appointed to oversee the entire operation.
His Majesty had even given additional instructions: once the resettlement was complete, Wei Zheng was to travel north again, collect the bones scattered along the Great Wall, and perform imperial rites on the emperor's behalf.
Thinking of the Great Wall, Hou Junji realized his thoughts had drifted again.
At that moment, snippets of conversation from the roadside reached his ears.
"The Five Thunder Temple has shown its power again!"
"Could it be the Thunder Lord's wrath?"
"After the New Year, they say a Daoist was nearly struck dead—only saved because an imperial physician arrived in time."
"It must be because the temple refuses to open its gates for common prayers. That angered the Thunder Lord!"
Hou Junji shook his head inwardly. But the interruption sparked a thought.
He knew where to go next.
A quarter-hour later, standing before a medical aide whose eyes kept darting around, Hou Junji was already losing patience.
"Where is Sun the Medicine King?" he demanded. "Don't tell me he's not here either."
Thanks to the later generations' emphasis on medicine, the Imperial Medical Office had undergone reforms since Sun Simiao agreed to remain in service.
It was now divided into medical practice and pharmacology. Entry required examinations. Monthly, seasonal, and annual assessments were mandatory.
Graduates became medical aides, with ranks above that progressing through physician, senior physician, medical doctor, and beyond. The Medical Deputy managed the office, while the Medical Director held final authority.
That position was currently held by Sun Simiao himself.
"Sun the Medicine King is here," the aide stammered, "but… it's inconvenient for him to see guests."
Hou Junji had failed to find Fang Xuanling at the Imperial Academy. He hadn't seen Li Jing or Li Shiji at Five Thunder Temple. Now, after finally finding one member of the Ganlu Hall circle, he was being turned away?
He had reached his limit.
With a sharp wave of his hand, he ordered his retainers forward, shoved the aide aside, and strode straight into the Imperial Medical Office.
The interior was sparsely furnished. A medical doctor hurried over—he recognized Hou Junji immediately. Seeing the aide frantically gesturing behind him and the duke's retainers bristling with menace, the man felt his scalp go numb.
"Duke of Lu, please wait a moment. It truly isn't convenient for Sun the Medicine King to receive visitors right now. Allow me to announce you first."
Hou Junji nodded, but his tone left no room for refusal.
"Tell him this: today, no matter what, I must see him."
The unease in Hou Junji's heart had been building all day, pressing down on him until it was almost panic.
Looking back now, even Xuanzang's parting words—'take care of yourself'—seemed loaded with meaning.
The medical doctor left with a troubled expression.
Moments later, he returned.
"Duke of Lu, please follow me. Sun the Director says… he needs your help."
Seeing the man's visible relief only made Hou Junji more uneasy.
The walk was short. They stopped before a room near the back. At the door, the medical doctor refused to go any farther.
"Sun the Director is waiting inside."
Hou Junji didn't hesitate. He pushed the door open.
The room was dim. At first glance, Hou Junji saw Sun Simiao busy at work. Relief rose in his chest—
Then his eyes focused.
On the table lay a man who had been completely opened up.
Sun Simiao, utterly unbothered, even had time to ask for assistance.
"On the shelf to the left—there's a short knife, blade half a finger long. Hand it to me."
Hou Junji swallowed hard. Nausea surged up, only barely forced back down.
He had seen plenty of corpses before. But never anything like this.
"Medicine King… this—"
"His Majesty has approved it."
Sun Simiao cut him off, clearly irritated.
Hou Junji fell silent at once.
Sun Simiao seemed accustomed to this argument by now. He spoke without pause.
"Dissecting the body to find the source of illness—Wang Mang did it. The Song dynasty did it. Later generations do it. Why should Tang not?"
"If you can't help, then don't stand there causing trouble."
Hou Junji obeyed. He backed out.
He waited at the Imperial Medical Office until evening before Sun Simiao finally emerged.
Seeing Hou Junji's hesitant expression, Sun Simiao spoke bluntly.
"A condemned prisoner from the Court of Judicial Review. Died of illness."
Only then did Hou Junji relax.
Sun Simiao studied him carefully, then suddenly asked:
"Duke of Lu, do you think I'm bold?"
There was no need to think. Hou Junji nodded vigorously.
Sun Simiao smiled faintly.
"You are far bolder than I am."
Hou Junji didn't understand.
Sun Simiao shook his head, fatigue written across his face.
"The questions troubling you should be asked of His Majesty. Go home."
Watching Hou Junji leave in confusion and anger, Sun Simiao sighed inwardly.
This was one of the reasons he disliked the capital.
He dissected a condemned criminal who had died of illness, and suddenly the entire Medical Office treated him like a monster—forcing the emperor himself to issue orders in support.
Yet these self-satisfied nobles thought nothing of schemes that could cost hundreds or thousands of innocent lives.
Still…
With the emperor enlightened by knowledge from later ages, medicine was now valued as never before.
For that alone, Sun Simiao decided to ignore what he could.
Hou Junji's anger lasted only through the night.
Early the next morning, an imperial messenger arrived with an edict: Duke of Lu Hou Junji was to proceed north of the city to observe a demonstration.
Sitting in his carriage, Hou Junji stopped trying to guess.
Whenever matters involved His Majesty, what he thought rarely mattered. What mattered was what the emperor thought.
That was a lesson learned from years in the Prince of Qin's household.
But where had things gone wrong?
Thinking back carefully, His Majesty's expression when sending him off in the first month had seemed sincere.
So there was only one possibility: during his time in Hexi, the emperor's view of him had changed.
Was it the court? Or Ganlu Hall?
The court was quickly ruled out. If the Censorate were accusing him, they would shout it from the rooftops. He would have heard something.
That left only one answer.
The Ganlu Hall light screen.
At that point, there was nothing to analyze.
Hou Junji could devise the Xuanwu Gate plan through layered intelligence analysis—but he could not predict what a young man from over a thousand years in the future might say, or how that could place the Duke of Lu in such an awkward position.
North of the city, the Imperial Guards had cordoned off an open area, resembling a temporary military camp.
Li Shimin stood on elevated ground. Beside him were Li Jing and Li Shiji, both smiling, and Yan Lide, his expression calm.
From afar, Li Shimin glanced at the sullen Hou Junji climbing down from his carriage. He snorted softly, then turned to Li Jing.
"Has the gunpowder you've been studying finally taken shape?"
Li Jing nodded openly.
"After examining ancient texts, we used saltpeter as described in Fan Zi Jiran as the base, then tested formulas derived from Daoist elixirs."
"The Daoist Songcheng of Five Thunder Temple shows particular talent. What he produced yesterday was thunderous, smoke soaring skyward—very close to what later ages describe."
Li Shimin recalled the scenes he had seen on the light screen, and the Daoist who had once blown up his own furnace. Enlightened by later knowledge, he now understood how valuable such rare talents were.
After a moment's thought, he asked:
"And that Daoist Songcheng…?"
Li Jing shook his head.
"The Daoists now only handle the mixtures."
"Yesterday, Songcheng observed from afar. The guardsman who ignited the powder lost hearing in one ear."
Li Shimin exhaled. Acceptable.
"Reward both the injured guardsman and Daoist Songcheng generously."
The brief exchange ended. It was time to see the results.
Imperial Guards from Five Thunder Temple entered the field. Three hundred paces from the emperor, they dug a pit and lowered in a jar large enough for a man to embrace.
They filled it in, then laid out a thick fuse.
Shielded by several heavy shields, Li Shimin craned his neck to watch.
The guard lit the fuse with a torch, then fled as if his life depended on it.
The spark raced forward, vanished underground.
The sound was muted by the earth—but the effect was undeniable.
Dirt rained down like a sudden storm.
A massive crater was left behind. A horse tethered nearby to test the blast's power no longer had a recognizable shape.
Yan Lide's face darkened.
The heavy infantry and cavalry he had refined not long ago… against this, they would have little chance.
Li Shimin, Li Jing, and Li Shiji all fell silent.
Li Shimin recalled the hellish silhouettes of future warfare he had seen in the Martial Marquis Shrine segment.
At last, he spoke.
"This thing—later generations use it to kill in war. They also use it to reach the heavens, to explore the mysteries of the world."
"How it is used depends on the heart."
He was no longer the Qin Prince of ten years past.
Had he obtained this then, he would have found a way to blow someone like Dou Jiande to pieces and laughed in triumph.
Now, his first thought was different.
Beyond killing, how could this thing add brilliance to a flourishing age?