The shadow of the sundial in Jinling City had just passed the hour of Si, and the atmosphere at the Imperial Merchant selection arena was thick with tension. Shen Xitang stood on a stage constructed of thirty-six layers of wooden steps. In her hand, the Skysining Brocade fluttered in the breeze, the Big Dipper pattern on its surface shimmering as the light shifted. This was the "Xuanji Dye" she had developed using minerals from underground canals, as recorded in the *Canal Dragon Vein Map*; every starlight mark corresponded to the precise location of hidden engineering piles.
"Submitted by the Suzhou Textile Bureau—Cloud Phoenix and Pearl Brocade!"
As the judge announced the entry, eight burly men heaved a gilded loom onto the stage. Shen Xitang caught a glimpse of the entwined floral pattern on the shuttle and suddenly snapped the gold-thread bracelet on her wrist. The agate beads rolled toward the loom’s base—the reflection from the beads revealed traces of hidden sulfur powder. It was a poisonous scheme to ignite the loom through the friction of its operation.
"Wait!" She whipped out the Skysining Brocade, unfurling it. "I request to inspect the Suzhou loom!"
Xiao Heng’s steel whip lashed through the air, coiling around the judge's wrist just as he was about to strike the gong. Shen Xitang seized the moment to throw a Pear Blossom Rain Needle canister; the steel needles pierced the loom’s rotor, causing sulfur powder to rain down. The arena erupted in an uproar. Beneath the python-patterned robe of the Suzhou Textile Bureau ambassador, a pair of custom-made iron knee guards from the Ministry of Works was faintly visible.
"Does Mistress Shen realize the penalty for making false accusations?" The judge demanded, his face ashen as he raised his bronze gong.
"I request to test the machine to prove my claim!" She unfastened her modified sash, revealing the Armillary Secret Key hidden within. "If this machine is found harmless, I will accept the punishment of facial branding."
Twenty waterwheels on the stage suddenly roared to life; these were the test mechanisms installed by the Ministry of Works. Shen Xitang inserted the secret key into a hidden slot on the loom. Layers of iron armor peeled away, revealing three thousand threads of ice-silkworm gold silk. As the first length of Skysining Brocade was woven, the Suzhou loom suddenly burst with sparks. Amidst the indigo flames ignited by the sulfur, the hidden seal of the Ministry of Works' Tiger Tally appeared.
"A brilliant display of the 'Fire-Washing Revelation'!" Xiao Heng’s steel whip shattered the curtain of fire. "This sulfur is mixed with malachite powder—it reveals the Ministry’s secret seal upon contact with heat!"
In the chaos, Shen Xitang grabbed the copper pipe of the test waterwheel. The siphon device drew water from the Qinhuai River onto the stage, and as the water passed through the hidden Xuanji dye vat, it turned deep indigo. She dipped the Skysining Brocade into the water curtain, and the map of the winding canal—the exact layout of the Ministry’s secret piles—appeared on the fabric.
"Seize the arsonist!"
The cry from a scarred boatman jolted the crowd. Shen Xitang saw the Suzhou Textile ambassador vault off the stage, his python-patterned robe flickering among the rooftops. She tore down the Skysining Brocade and threw it toward the guards. The phosphorus-soaked fabric unfurled in the wind like a net, ensnaring the fleeing man. Under the moonlight, the canal map on the brocade revealed his exact escape route.
"Lord Xiao! The third arch of the Vermilion Bird Bridge!"
The steel whip coiled around the bridge pillar, and Xiao Heng swung into the canal. Shen Xitang pulled the mechanism key on the stage, causing the test waterwheels to reverse direction, twelve pillars of water sealing off all escape. When the iron net caught the suspect, his gilded fish-tally collided with the Armillary Secret Key, and the sparks produced in the night sky spelled out the characters "Guiyou."
At the fifth watch, Shen Xitang stood in the evidence room of the Court of Judicial Review. The Skysining Brocade, soaked in alum water, revealed a new map—it pointed to Yanziji, where a canal boat had sunk twenty years ago, marking a hidden Ministry of Works warehouse on the riverbed. She pressed the Armillary Secret Key into a gap in the parchment, and seven indentations appeared on the key, corresponding to the "Seven-Star Anchoring Method" described in the *Essentials of River Engineering*.
"Mistress Shen, look at this." Xiao Heng pried open a sealed box with his steel whip, revealing half an iron anchor. "This was found on the suspect. The claw patterns..."
"They are of the same origin as the *Xuanji*!" Shen Xitang traced the Big Dipper patterns etched into the anchor. "The shipwreck back then wasn't an accident; someone intentionally chiseled through the hidden warehouse!"
As morning mist crept into the window, the scarred boatman delivered an urgent report: a sudden sinkhole had opened at Yanziji, revealing rows of blue-brick storage vaults. Shen Xitang spread the Skysining Brocade on the table; the mineral patterns revealed by heat matched the location of the vaults perfectly. She suddenly tore open the lining of the brocade, exposing hidden ice-silkworm silver silk—the finest quality, quenched in the cold springs of the underground canals.
"Immediately refit the test vessel!" She pressed the Armillary Secret Key against a spot on the *Canal Dragon Vein Map*. "We will use the Seven-Star Anchoring Method to salvage the sunken iron!"
At the third quarter of the hour of Wei, the vessel locked across Yanziji. Shen Xitang stood before the modified crane, twenty iron anchor claws descending into the river. When the winch turned for the seventh time, the river churned as if boiling. It was not sunken iron that rose from the vault, but crates of "Artillery Manuals"—each wax seal bearing the joint stamp of both the Ministry of Works and the Ministry of War.
"Mistress Shen, look out!"
Xiao Heng’s steel whip deflected a volley of cold arrows. Shen Xitang crouched behind a wooden crate and saw a python-patterned figure dart across the cliffside. She grabbed the Skysining Brocade and draped it over a telescope; through the phosphorus-traced patterns, she clearly saw three cinnabar moles on the man's arm—it was the old boatman from the Shen family who had supposedly "drowned" twenty years ago.
"Fire the repeating crossbows!" She pulled the mechanism key, and the ship’s side panels flipped open to reveal twelve bed crossbows. "Seal the eastern pass with sulfur arrows!"
In the melee, Shen Xitang slipped into the vault. Embedded in the layers of blue brick was half a rotted account book. The ink oxidized rapidly in the air, revealing a shocking string of numbers: from the first to the fifth year of Jiajing, the Ministry of Works had secretly purchased three thousand six hundred stone of Japanese copper, all of it cast into official counterweights.
"So that's it!" She pressed the account book against a test weight. "The missing seven qian from the official weights was to cover the deficit from the Japanese copper smuggling!"
The river wind shifted, and the vessel swayed violently. As Shen Xitang stumbled against the iron anchor chain, she caught sight of sulfur corrosion marks on the links. Realizing the truth, she grabbed the copper pipe from the waterwheel and poured river water over the chain—as the water washed away the grime, the Big Dipper patterns revealed by the corrosion matched the notches of the Armillary Secret Key perfectly.
"Lord Xiao! Raise the anchor!"
The steel whip severed the cable, and the vessel used the river's force to ram into the cliff. As the ship shattered with a deafening roar, Shen Xitang leaped onto the reef, the Skysining Brocade in her hand unfurling like wings. The phosphorus tracking marks pointed to a cave on the cliff face, where twenty iron crossbows glinted in the morning light—these were the lost Yongle Shenji Crossbows of the Ministry of Works.
"Little girl of the Shen family, you found your way here after all."
A hoarse voice echoed from the depths of the cave. An old man in a python-patterned robe walked out slowly. The gilded counterweight in his hand was engraved with "Made in the First Year of Jiajing," and sulfur powder leaked from its base.
Shen Xitang stared at the face so similar to her father's, a surge of complex emotions rising within her. Suddenly, as if she had made up her mind, she tore open the casing of the test weight. With the shell removed, a tattered page of the *Essentials of River Engineering* was revealed. Surprisingly, it contained a portrait of the old man from his youth—he was the spitting image of the person standing before her.
Shen Xitang took a deep breath, her gaze piercing like a torch, and said coldly, "Uncle, have you been well?" Her voice was icy and laced with irony.
Without hesitation, she pressed the Armillary Secret Key onto the crossbow's rotation wheel. With a faint mechanical click, the crossbows were activated.
"Back then, for your own greed, you altered the official weights, causing the Shen family's cargo ships to be overloaded and sink, costing countless lives. Today, it is time for you to pay that blood debt!" Her words struck like a sword.
At that moment, the morning sun pierced through the dense fog, illuminating the entire river. On the nearby cliff, the twenty modified lifting mechanisms, like sleeping giants, were awakened by the dawn.
Shen Xitang leaped gracefully onto the imperial merchant's stage and unfurled a massive Skysining Brocade. The morning light filtered through the fabric, hitting the Big Dipper pattern and creating a strange, ethereal sight. Behind this spectacle, projected onto the water curtain, was the complete *Canal Dragon Vein Map*. It detailed the course of the canal and the location of the dragon veins, a secret the Shen family had guarded for generations.
As the judge held up the Shen family's golden seal high, Shen Xitang’s gaze moved past the crowd, toward the distant Yanziji. There, a wisp of black smoke rose slowly, as if a signal, heralding the truth that had been buried by the Ministry of Works for twenty years.