"Do you hear that?" Macan said, drawing her axes from their sheaths. Her sharp ears were filtering the howling of the cave. "That isn't the whisper of trees. That is... the scream of a suffering mechanism."

  When the heavy cast-iron doors of the Combustion Chamber creaked open, a dense cloud of throat-burning steam wafted out. In the room, nested between the pistons, stood Brass-Shelled Spiders

  Eren pulled his heavy metal mace—engraved with silver but blackened by gunpowder soot in places—from the hidden holster inside his coat. This looked nothing like the dainty wands mages used; along its body ran thin brass pipes, a miniature steam boiler, and a small, trembling pressure gauge. When Eren flicked the safety catch on the handle of the mace, a low-frequency growl and sharp steam rose from within the metal.

  "Marry, protect the light!" Eren shouted.

  As the largest spider descended like a shadow from the massive piston above them, Eren took a firm step toward it instead of retreating. While the creature’s scalpel-sharp leg grazed Eren’s shoulder and tore his cloth, Eren squeezed the trigger of his mace with all his might.

  "CRACK!"

  The heavy metal head at the end of the mace launched forward with immense pressure, shattering the spider’s hard brass shell like paper. Immediately after the impact, superheated steam sprayed from the mana tube inside the mace, scalding the creature's internal organs in seconds. Eren professionally shouldered the powerful recoil of the weapon with his shoulder and chest muscles; it was clear he had fired this mace thousands of times, familiar with its every shudder.

  "It still makes the same rusty noise," Eren murmured, waving away the black smoke rising from the tip of the mace. "Just like its owner."

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  When they stepped into the Control Room, the ear-piercing mechanical noise of the dungeon gave way to a heavy, oppressive silence. This was the brain of the machine. Thousands of brass gauges running along the walls and glass pipes through which shimmering liquid mana flowed displayed how the underground river was being ruthlessly exploited like a map.

  Atop the main console in the very center of the room sat an origami in the shape of a pyramid, meticulously folded from blood-red paper. The red paper flickered slightly, as if feeding on the intense mana flow in the room.

  "Don't touch it," Marry said. This time her voice echoed with professional caution rather than fear. "This is a 'Voice Carrier'. The killer has left a seal, a message here."

  Eren lightly touched the cold metal tip of his silver-engraved mace to the paper pyramid. The moment he touched it, the paper began to unfold like a living insect, spinning rapidly on its own axis. A muffled but authoritative voice, resembling the howling of the wind, echoed through the room:

  "Welcome, Chief Inspector Eren. If you are hearing this voice, it means you have survived the lies in Lord Pitrosg’s magnificent manor. But I wonder... did the Lord tell you that this dam only stole mana? Or did he forget to mention that this mana was being sold not to the Great Witch's palace, but to the enemy elves at the kingdom's border to manufacture mana weapons?"

  Aslan took a step back in shock, the metallic clatter of his armor breaking the silence. "Treason? Is Lord Pitrosg betraying the kingdom?"

  The voice continued with a cold sneer, as if it had heard their shock: "I am not a killer, Eren; I am a mirror. I built this monster created by the Lord here to drown him in his own filth. This dam is set to explode the moment the Elven Queen sets foot on our land. The decision is yours, Inspector: will you protect the system and save a traitor, or will you let yourself be crushed between the gears of the machine and allow the truth to come to light?"

  As the red paper turned into a pile of ash and scattered over the console, Eren gripped the mace in his hand so hard his palms nearly burst. The killer’s repulsive brilliance had thrown him onto the tray of an impossible scale. On one side stood the security of the kingdom and hundreds of innocents; on the other, the bloody secret of a treasonous noble.

  "Lowlife bastard," Eren said, striking his mace hard against the floor. The sound of metal hitting stone was like the first bell of the approaching disaster. "He is willing to throw the entire forest, us, and the truth into the same fire to ensure his own justice."