The roar of the water behind the granite slab was no longer a distant hum; it was a physical vibration that Sam could feel in the soles of his boots. The Black Ridge seemed to tremble under the weight of the trapped spring. If the blockage held, the pressure would eventually shear the entire cliff face off, sending a lethal slurry of rock and water straight down onto Oakhaven.
"We can't just pry it loose," Sam shouted over the deepening rumble. "If that slab shifts all at once, the vacuum will pull us right into the intake. We have to create a vent—a pilot hole to bleed off the air before the water follows."
Twinkle was already uncoiling the climbing rope, her face pale but her hands steady. "Tell me where to anchor, Sam. I'll hold the line while you work the fissure."
Sam pointed to a jagged spur of ancient bedrock ten feet above the blockage. "There. If the slab goes, that spur is the only thing that won't move."
He stepped onto the slick, vibrating surface of the granite stopper. His architect's mind was frantically calculating the load-bearing points. The slab was wedged in a classic "keystone" position, held in place by its own weight and the massive friction of the side walls. To move it, he didn't need brute strength; he needed to break the seal.
He jammed the iron pry bar into a narrow, moss-slicked crack where the granite met the cliff. He threw his entire weight against the iron. The bar groaned, bending slightly, but the stone didn't budge.
"Again!" Twinkle urged, leaning back against the rope to keep him balanced.
Sam Reset the bar, finding a deeper purchase. He closed his eyes, visualizing the silver channels of the fountain below. He wasn't just a man with a piece of iron; he was the final gear in a machine his grandfather had built a century ago. He exhaled, a sharp, guttural sound, and surged upward.
Crack.
The sound was like a rifle shot echoing off the canyon walls. A jet of high-pressure air, cold and smelling of ancient minerals, whistled out of the fissure. The vibration changed frequency, shifting from a low growl to a high-pitched scream.
"It's venting!" Sam yelled. "Get back, Twinkle! The seal is breaking!"
He scrambled back toward the safety of the ridge just as the granite slab began to moan. The water behind it, finally finding a path, began to geyser through the small opening he had created. Within seconds, the "pilot hole" eroded into a jagged maw. With a final, thunderous crash that shook the very foundation of the mountain, the ton of granite was spat out of the cleft like a cork from a bottle.
A wall of white, frothing water exploded from the intake. It surged down the natural stone flume, scouring away decades of debris and silt. For a moment, the mountain seemed to hold its breath. Then, the water cleared. The violent brown flood turned into a steady, powerful crystalline stream, flowing exactly as the maps in the secret chamber had dictated.
Sam lay on his back on the cold shale, gasping for air, his clothes soaked and his hands raw. He looked up at the sky, which was now a brilliant, cloudless blue.
"Did it work?" Twinkle asked, crawling toward him, her eyes wide with adrenaline.
Sam sat up and looked down into the valley. Far below, through the shimmering heat haze, he saw a flash of sapphire. The "Blueberry Heart" was no longer just pulsing; it was singing. The pressure had stabilized. The danger to the town had passed.
"It worked," Sam said, his voice ragged but triumphant. "The music is back to stay."