The cave dwelling was cool and dry, with a layer of dried mugwort on the ground, soft to the touch and carrying a stale herbal scent. A small patch of morning light slanted in from the cave entrance, turning the dust particles in the air into dancing gold dust. Snow Empress sat down on the mugwort, untied her cloak and spread it beside her, took out an oil paper package from her satchel, opened it, and found a few hard wheat cakes and a small packet of salted dried radish inside.
"Eat some first." She pushed the oil paper package in front of him.
Yin Wujou took a bite of a wheat cake, slowly chewing the dry, hard dough. The wheat aroma was faint, and the combination with the sour and crunchy salted radish made it especially delicious after walking all morning. As he chewed, he recounted to Snow Empress Di all the details he had seen that morning in the Imperial Astronomical Bureau —the layout of the study, the location of the hidden compartments, the density and direction of the Spiritual Power distribution, and the path of the gray-green aura.
After listening, Snow Empress didn't speak immediately. She broke the wheat cake into small pieces, soaked them in the cool water of her water bag until they softened, and then ate them. She chewed very slowly, her gaze fixed on the patch of light at the entrance of the cave, as if she were building the spatial map he had described in her mind.
"The study is located at the confluence of spiritual veins," she finally spoke, "And the hidden compartment is in the most concentrated area of Spiritual Power within the study. This shows that the location of the hidden compartment was carefully chosen by the Director of the Imperial Observatory—placing the most important items in the place with the densest Spiritual Power in the entire Imperial Astronomical Bureau is equivalent to using the dense aura of the spiritual veins to create a natural shield. Ordinary people entering the study cannot sense the existence of the hidden compartment at all, because the density of Spiritual Power is the same in all directions, making it impossible to discern where something is hidden. You were able to find it because your Spirit Vision is not affected by the density of Spiritual Power —what you see is the difference in the thickness of the aura, not the intensity of the Spiritual Power itself."
"So that grayish-green aura was also being guided by the spiritual vein?" Yin Wujou asked.
"Possibly." Snow Empress swallowed the last bite of the soggy wheat cake and wiped her hands. "The spiritual vein network is like an underground river, with Spiritual Power flowing along its bed. Anything that leaves even a trace of its aura within the spiritual vein network will be carried by the main vein to the place where the spiritual veins converge most densely—which is the study. That aura didn't enter the study; it only stopped outside the door, indicating that it wasn't pulled there by the spiritual veins, but rather pushed along. Someone is using it to probe the way."
What did the scouts want that thing to see?
"Look at me," Snow Empress said. Her tone was calm, but Yin Wujou detected a hint of tension beneath. "That aura stopped outside the study where you were hiding, which means it sensed other Spiritual Power residue besides the Supervisor's aura. It stopped to assess the situation, and then dissipated, essentially sending a signal back to its owner—someone has been in the Supervisor's study. That person should now know that someone has taken the Night Watch token."
Yin Wujou's spine tightened. "Shall we still go to the storeroom?"
"Go," Snow Empress said. "The token has already been taken. If we don't go, the other side will be setting up defenses in the warehouse and waiting. Going there might give us a chance to finish the job before they complete their setup. The longer we delay, the more passive we'll become."
She carefully wrapped the oiled paper and put it back in her satchel. She stood up, walked to the cave entrance, and looked out at the sun's position. "It's just past noon. According to the Imperial Astronomical Bureau's schedule, noon to 1-3 PM is the shift change time. The guards in the storeroom will change shifts around that time, with a gap of about half an hour. This is the best window of opportunity to sneak in. After that, around 3-5 PM, the night shift will be in place, and the storeroom will be locked with protective barriers. Even with a token, you might not be able to get in then."
Yin Wujou also stood up. He brushed off the mugwort leaves and cigarette ash from his clothes, and reopened his Spirit Vision, maintaining it at a level where he could clearly perceive the surrounding Spiritual Power fluctuations. "I'll go with you. You hold off the guards at the warehouse door, I'll go in and find Pei Yuan."
Snow Empress looked at him, her gaze lingering on his face for a moment. Morning light streamed in from the cave entrance, carving a clear line between light and shadow on her profile; the brighter half was bathed in warm sunlight, while the darker half remained hidden in shadow, its expression unreadable. "After you enter the storeroom, you must find Pei Yuan within an incense stick's time, find out how the records went missing, and then leave. If you can't find him within an incense stick's time, leave immediately; don't linger. Many of the spiritual artifacts in the storeroom have been stored there for a long time and are imbued with remnant spirits. If you stay inside too long, your own aura will be eroded by those remnants."
"Good."
The two men left the cave, untied their horses, and followed a wild path behind the brick kiln, almost completely covered by weeds, back towards the Imperial Astronomical Bureau. The midday sun was blazing; although it was late autumn, the sunlight still carried a dry warmth. The foxtail grass by the roadside was bleached white by the sun, its fine thorns gleaming with a fuzzy golden light. On both sides of the path were large, barren vegetable fields; the radishes and cabbages had long been harvested, leaving only withered stubble standing in the hardened yellow soil like rows of old nails stuck in the ground.
The east wall of the Imperial Astronomical Bureau came into view. Unlike the west wall, this one wasn't covered in ivy; the wall was bare blue brick, with a layer of light gray plaster applied to the surface, presumably for moisture and water resistance. At the base of the wall was a side door, small, barely wide enough for one person, its sheet metal panel rusted and the brass rings covered in a layer of verdigris. Next to the side door was a small guardhouse, with a gray tile roof and walls made of broken bricks and mud; it looked very simple, completely incomparable to the main building.
Snow Empress dismounted in front of the guardhouse. She tied the reins of her green horse to a wooden post by the door, straightened her clothes and cloak, and walked towards the guardhouse. Yin Wujou followed a few steps behind her, his chestnut horse tied to another crooked willow tree nearby. He saw that the door to the guardhouse was half-open, and he could hear a man humming a muffled tune coming from inside—the melody jumped around carelessly, and he couldn't make out what song it was.
"Who goes there?" The man in the duty room heard footsteps outside and pushed open the door, peeking halfway out. He was a middle-aged man in his forties, with a dark reddish-brown face and a bluish stubble on his chin. He wore a drab gray short jacket with the sleeves rolled up above his elbows, revealing his tanned arms. When he saw Snow Empress, his gaze swept from her face to her cloak, then to Yin Wujou behind her, and finally back to Snow Empress's face, his eyes narrowing slightly.
"From the Spirit Vein Bureau." Snow Empress pulled a wooden plaque from her waist and handed it over. A line of blurry official lettering was engraved on it. Yin Wujou didn't know where she got it, but it looked very real. "They're here to check the registration of a batch of old spirit artifacts in the storeroom. Those of you on duty should have received the supervisor's notification by now?"
The man took the wooden plaque and examined it twice, then looked Snow Empress up and down for a moment. His expression didn't reveal whether he believed it or not, but he had already handed the plaque back to Xue Di.