Early the next morning, Xu Jinghong did not go to the Salt Tax Office first.
She went to Ji'an Hall Pharmacy.
Qin Zhao followed behind her. Only when they reached the shopfront did it hit him. "We're looking at medicine before we look at the door?"
Xu didn't slow. She gave him one sentence, clean as a rule:
"The door won't run.""People do.""A prescription can write the person into existence first."
Qin Zhao understood half of it and didn't press.
Ji'an Hall had just opened. The medicine-gourd plaque still hung outside. The same assistant from last night—the one with a callus at the thumb web of his right hand—was lifting the shutters.
Inside, the herbal smell was thick. Cabinets lined the wall in neat grids, drawer fronts labeled: licorice root, astragalus, fritillary bulb, pinellia, poria. The shopkeeper sat deepest in the room, abacus still cold under his fingers.
Xu Jinghong didn't step up to the counter right away.
She stood at the threshold and watched.
Watched what?
Three things.
Who arrived early.Who went behind the inner counter.Who touched last night's small paper parcel.
Before long, a child came out from the back carrying a small black jar like the one from last night.
Not ginseng broth—medicine.
The jar's mouth was sealed with paper and cinched with fine cord.
The shopkeeper glanced at it and asked only one question:
"Did that gentleman cough hard again last night?"
The child nodded. "After midnight it flared again. Mr. Shen said to change the formula."
Qin Zhao's pulse kicked.
Mr. Shen—who else could that be but Shen Weijun?
The shopkeeper asked no more. He stood and went behind the inner counter himself.
That was wrong.
For ordinary customers, an assistant would measure and wrap. When the shopkeeper does it personally, it means the formula is expensive—or the patient is not someone you can offend.
Only then did Xu step forward. She set two copper coins on the counter and spoke evenly:
"My family elder coughs too. Slept badly last night—do you have any ready-made cough powder?"
The shopkeeper looked up at her once and answered offhand, "Coughs come in cold and heat. I don't dare give ready-made medicine blindly."
Xu nodded. "Then don't. I'll just see what you keep as standard stock, so I can explain to the elder at home."
It wasn't a strange request. Old coughs were everywhere in the city.
The shopkeeper lowered his eyes and began measuring medicine, no longer paying her attention.
Xu stood at the counter and watched his hands.
First he took fritillary.Then lily bulb.Then a pinch of ginseng whiskers, fine as thread.Last, instead of dropping in a common cough pill, he opened a packet of dark brown powder and shook a little into the mix.
Qin Zhao didn't understand the ingredients, but he memorized the sequence.
When the shopkeeper finished, he handed it to the child from earlier and gave precise instructions:
"Don't simmer it long this time. Bring it to one boil and serve.""Ginseng broth as usual. Separate broth and medicine by half an hour.""And today—don't let him write past the second watch."
The child nodded and left with the jar.
Qin Zhao understood at once.
The extra person behind the black door wasn't merely "sick."He was sick enough that he couldn't truly endure—yet he was still forcing himself to write.
Qin Zhao was about to speak. Xu's eyes flicked toward him—just once.
The message was simple: not yet.
When the child had gone far enough, Xu murmured:
"Follow the medicine jar. Don't follow a face. Watch which door the jar enters."
Qin Zhao nodded and slipped out.
Xu did not follow.
She needed a second thing: the shop copy of the prescription.
Old pharmacies don't keep only one script. The patient gets a written order to carry away, but the shop keeps a retained record—the root copy that proves what was prescribed.
A prescription can walk. The root copy leaves a stump.
The shopkeeper had barely sat down again when Xu lowered her voice another notch.
"Shopkeeper, my elder has coughed for years. That formula you just made—sounds like it supports the lungs, not something that drives out cold."
The shopkeeper's hands paused. He finally looked at her properly.
"You know medicine?"
"I don't," Xu said. "But when a house lives with illness, you hear enough to learn half."
The shopkeeper snorted. "Half is what you know. That formula isn't supporting the lungs. It's propping the breath."
"Propping… the breath?"
"The man's too weak, and the cough is heavy. Too mild and it won't suppress. Too strong and it harms the body.""So you stop the cough with one hand and keep the breath suspended with the other. Otherwise he can't sit still—can't write."
He realized he'd spoken too far and shut his mouth immediately.
But it was already enough.
Can't write.
Inside Xu Jinghong, the line snapped into place.
She feigned a casual follow-up. "A formula like that—does it go to scholars?"
The shopkeeper didn't answer. He slid the abacus forward and flicked a bead. "Ask too much and I won't sell."
Xu didn't press.
She drew out a small shard of silver and pushed it across—no bargaining, only one sentence:
"I'm not asking for a name.""I want to know whether this is a chronic illness—or a temporary strain."
The shopkeeper stared at the silver, then glanced at the door. Finally he gave one true line:
"Chronic.""Damage in the lungs. Worse at night.""Usually manageable. But one sleepless night, one anger—then you add ginseng."
When he finished, he pushed half the silver back.
"That's all. More than that, I won't dare say."
Xu took back the half and left the other half untouched.
She had already gotten what mattered most:
It wasn't a performance—it was an old illness.The patient couldn't write long, yet had been forcing it for days.And Shen Weijun could intervene directly in the prescription.
That meant the unseen "fourth person" behind the black door likely sat at the very desk where the grand seal could be made to fall.
Qin Zhao returned quickly.
He didn't enter the pharmacy. At the alley mouth he gave a light cough—Xu recognized it as a signal at once.
She stepped outside. Qin Zhao reported in short, clean lines:
"The medicine jar didn't go through the main entrance.""It went through the black door again.""The key-clerk glanced at the paper seal and let it through.""Before entering, the child said: 'Registrar Gu—broth first, medicine after.'"
Xu stopped.
Qin Zhao, afraid he'd misheard, added, "I heard it clearly. Registrar Gu."
Registrar Gu.
At last the "fourth person" inside the black door had a title.
Not Shen Weijun.Not the gray-jacket hook-writer.Registrar Gu.
Qin Zhao asked softly, "Is he the one who controls the grand seal?"
Xu didn't rush to declare it. She laid out what they already knew, one line at a time:
"The gray-jacket man draws the hooks.""Shen Weijun reads, validates, and makes paper effective.""Registrar Gu is ill—and still forcing himself to write, to take medicine, to drink ginseng.""And his medicine must pass through the black door."
Xu looked toward the Salt Tax Office and finally spoke the relationship all the way through:
"If the door recognizes paper, and paper recognizes a validation mark, and the mark recognizes the seal—""then Registrar Gu is either the one who reviews the seal, or the one who guards it."
Qin Zhao's back cooled in slow waves.
So the most dangerous person behind the black door wasn't the baton-holder. Not the runner. Not the courier.
It was someone sick, hidden, never appearing—yet still able to decide who got sealed behind gates, who got called out by name, who got detained.
Harder to fight than he'd imagined.
"What do we do now?" Qin Zhao asked.
Xu's answer was steady.
"Three things are fixed now."
"First: there is indeed an extra person inside the black door—Registrar Gu.""Second: he has a chronic lung condition. At night he needs ginseng broth and medicine to keep his breath propped.""Third: he has been forcing himself to work for days, which means something must be finished today."
Qin Zhao caught it fast. "The master register?"
"Most likely," Xu said. "Possibly also the final draft for the gate-sealing notice."
Then she pushed it one step further:
"Men like this don't move on ordinary days.""They move only when two things fail—""when the medicine runs short, or when the paper runs short."
Qin Zhao's eyes brightened. "So we don't crash the door—we cut his medicine, or cut his paper?"
Xu shook her head.
"Cut the medicine and you trigger panic.""Cut the paper and you trigger chaos.""It's not time to startle him yet."
"What we do is make him leave his desk—if only for a quarter-hour."
"As soon as he leaves the desk, the space behind the door is empty for one breath.""And that breath becomes our door."
Qin Zhao understood, but his chest still tightened.
"How do we make him leave?"
Xu Jinghong looked at the medicine-gourd plaque and said, slowly, as if writing a rule:
"A man this sick, still forcing himself to write, fears two things most.""First: the medicine is wrong.""Second: the prescription leaks."
She turned to Qin Zhao.
"Tonight—we do it again.""This time we don't watch food. We watch the prescription."
"We take Registrar Gu's root copy."
Qin Zhao blinked. "From the pharmacy?"
"Yes." Xu's voice didn't lift. "A prescription isn't just paper. It's a gate.""If we take the root copy, we pull the person behind the black door half a step out from behind his desk."
Historian's Note: The thing that truly crushes an era is often not the strongest man, but the man who cannot stop. Once such a man holds seal and register, humiliation is written into procedure. And to rewrite history, you sometimes begin—with a single prescription.
(End of Chapter.)