The moment the cave entrance opened, a startling wave of heat rushed out, hot enough to nearly set a person's hair on fire.
Tang Changsheng seemed not to notice. He strode inside and saw a huge furnace built deep within the cave. At first glance, it looked like an ancient iron forge.
Especially when dark red flames tinged with blue flickered from it, sending up a tremendous heat.
A man, blackened from head to toe, sat cross-legged inside. At the sound of movement, he stood at once. "Master, you're here!"
Tang Changsheng nodded slightly. "The fire's burning well..."
The man shrugged. "It's nothing special. Throw one brick in, and it'll burn all day..."
As he spoke, he pointed to the neatly stacked black bricks in the corner. Each was three feet long and one foot wide, apparently pressed from coal, and looked as big as a brick from an ancient city wall.
His casual attitude made Tang Changsheng laugh and scold him. "Do you know how much one of those costs? You could work as a policeman your whole life and probably only afford one or two!"
That was an exaggeration, but not an empty one. On closer inspection, the bricks were not entirely black. Flecks of vermilion light glimmered within them, lending the coal bricks an eerie, mysterious air.
Even with Tang Changsheng's wealth, the sight made his heart bleed.
Although coal was the main ingredient, the fact that a single brick could burn for an entire day showed these were no ordinary things.
In fact, they were made to a secret formula, with who knew how many precious substances mixed into the coal. For one thing, those flecks of red light came from crushed Fire Marrow Crystal.
A Fire Marrow Crystal the size of a fist was worth