"Put that down," the Gatekeeper ordered, and its voice had changed, become deeper, less human. "You know not what you have done."
James shook his head. "I know exactly what I've done," he said.
"You cannot defy me!" the Gatekeeper roared, and it revealed itself once more. It no longer looked human, however, but like an enormous cloud of swirling smoke and ash. Eyes swarmed through the cloud, all of them furious, glowing red. "No one can defy the Gatekeeper! Release the stone! You cannot contain its power!"
"That's true," James said, no longer afraid of the Gatekeeper, "but I know someone who can."
He turned, somehow knowing that Merlin would be standing nearby. Perhaps James had even somehow caused him to be there. He walked over to the big wizard and held out his hand. In it, the ring sparkled brightly. Darts of light flashed off the black facets of the Beacon Stone.
Merlin smiled a slow, humorless smile. Gently, he took the ring and placed it on his finger, seating it alongside its twin.
"And now," Merlin said, raising his hand, "as your earthly Ambassador and bearer of the complete Beacon Stone, I command you! This is not your world, nor shall you occupy it! Begone, Beast of the Abyss, Gatekeeper of the Void! I banish you to the nothingness that shall forever be your home! Depart this moment, and never return!"
The cloud of ash and smoke roared. It made to fall upon Merlin, attempting to consume him, but a sudden, enormous crack of vivid light appeared in the darkness, slashing it open. The roar of the Gatekeeper turned into a shriek as it was pulled upward, toward the crack. It fought against the force, spinning and writhing, and for a moment, James thought it looked like a huge, inverted cyclone. And then, with a blinding flash and a clap of thunder, it was gone, banished back to the Void from which it had come.
James blinked in the silence. He took a deep breath and turned back to Merlin, exhausted.
"Is it gone?" he asked. "Gone for good?"
Merlin nodded slowly. "The door between the worlds is shut."
It was over. James turned to look back, curious to see if there was any remaining sign of that blinding crack into which the Gatekeeper had vanished. There was nothing but blackness and silence. And then—
There was a flash and James stumbled; light and noise exploded around him. He squinted, gasping for breath in the sudden noise and rush of air; he was back on the rear of the Hogwarts Express engine again, as if he'd never left it. Trees blurred past, just as before, but when James looked out over the coal car behind him, the air was bright and clear.
"The Dementors are gone!" he called to Merlin.
"Sent back to the Void along with their master," Merlin agreed, nodding.
James grinned in relief, and then suddenly remembered the train's perilous destination. "We have to stop the train!" he yelled, his eyes widening. "It's going to go off the unfinished bridge! Everyone on board will be killed!"
Merlin nodded again, his face turning grim. Once again, James opened the door of the engine compartment. Instead of darkness, however, this time he found a cramped interior space, stiflingly hot. At the front of the compartment was a bank of incomprehensible dials and gauges. Above this, two broad windows looked out over the oncoming track.
"Which one is the brake?" James called, scanning the dials and levers helplessly.
"That large lever on the floor," Merlin replied, pushing up his sleeves. "Grip the handle and pull as hard as you can, James. No matter what happens, don't let go."
James wrapped his hands around the large lever, which was nearly as tall as he was. He coiled to pull it but then made the mistake of looking out the front windows. The trees had cleared ahead, revealing a broad, mountainous panorama. The track stretched out before them, spanning a dizzyingly deep, rocky gorge, but only partially. Less than halfway across, the bridge stopped, unfinished. James' knees went weak.
"Pull it, James!" Merlin ordered, raising his arms, his face hard as granite. "Don't let go under any circumstance!"
James gasped a breath and yanked the lever as hard as he could with both hands. Gears below the engine's floor screeched and clanked as the braking mechanism engaged. Steam released explosively from the boilers on either side of the engine, sending up great white clouds. The train lurched and began to slow, but James knew there was no way it would stop in time.
Next to him, Merlin held up his arms. He was muttering quickly under his breath, his eyes closed. James looked up at him from where he stood, tugging the brake lever. The great sorcerer was trembling very slightly, nearly vibrating. Sunlight suddenly poured in through the engine's windows, and James knew they had cleared the trees at the cliff's edge. The train had begun its journey over the gorge, swiftly approaching the end of the bridge. Behind James and Merlin, nearly all of the students of Hogwarts and their teachers were hurtling along, breathless, possibly even clueless of their fate. The train continued to slow, its wheels grinding, screeching, sending up sparks, but it was no use. James craned to look through the windows and saw the end of the track approaching alarmingly fast. A wooden 'X' had been erected across it to keep workers from accidentally walking off the end. It looked pathetically fragile as the huge crimson engine bore down on it. And then, fleetingly, James saw motion at the end of the track. Something green was moving just beyond, so fast that he could barely see it. Even as James watched, however, the end of the track disappeared beneath the sightline of the engine's windows. He gritted his teeth, pulling the brake lever with all his might, and waited for the long, sickening drop.
The engine lurched noisily as if it had bumped over a curb, and James nearly lost his grip on the brake lever. Next to him, Merlin swayed but remained upright, hands still raised, still muttering under his breath. Amazingly, the train did not fall. It continued to move forward, pushed by the weight of the cars behind it, slowing almost imperceptibly. Like Merlin, the engine suddenly seemed to be vibrating. As it gradually lost its momentum, the vibration increased, becoming a noisy, jarring shudder that threatened to shake the engine apart at its bolts. One of the windows exploded in a starburst of glass, peppering the inside of the compartment with glittering shards. James winced as bits of glass and warm autumn air blew past him. A moment later, he craned to look through the broken window, his eyes wide and disbelieving as the gorge spread beneath the advancing train. The engine slowed, rattling and grinding until finally, after what seemed an eternity, it lurched to a halt. The sudden cessation of inertia threw James off balance and he stumbled to one knee, still gripping the brake lever.
Silence descended on the engine, shocking after the noise and chaos. It rang in James' ears. Shuddering, he took a deep breath and struggled to stand, shaking bits of glass from his hair.