“The House,” Billings continued, “was built as a barrier, to maintain the border between this world, the material world, and the other world, the Other Side.”

Mark’s mouth felt dry. “The ‘Other Side’?”

Billings’s eyes were flat, unreadable. “The hereafter, the world of the dead, the world of magic and the supernatural, the world of spirits. It is the opposite of this world, your world, and it is a horrific place, a world of terrors and abominations the likes of which you have never seen nor ever dreamed. The House was built to keep the two separate, and it is the only reason your people, your world, are still here. Otherwise, you would have been overrun long ago.”

Mark said nothing.

“The House is like an electrified fence or, more precisely, like a battery supplying power to that fence. And it is charged by people living within it. That is why you were called back. For the first time, the House is empty. There is no one living here, and the barriers are coming down. On both sides.” He looked at Mark. “Ever since Kristen passed on.”

Mark turned away, didn’t respond. His heart was pumping crazily, and his body was drenched with a sheen of fear sweat.

“The border is a semipervious membrane. It is not a solid wall, and without a strong barrier to separate the two worlds, they will inevitably collide. And that,” he said, “would be catastrophic.”

“So I’m here to recharge the battery?”

“If you will.”

“What happens if I refuse?”

“You have not refused. You have come.”

“What if I leave?”

“You can’t leave.”

“Who’s going to stop me if I break one of these windows and jump out and run away?”

Billings looked at him. “The House.”

There was silence between them after that.

“Where did the house come from?” Mark asked finally. “Who built it?”

“The Ones Who Went Before.”

The name, with its ambiguity and intimations of tremendous age, frightened him, and he listened quietly as Mr. Billings described the early days, after the barrier was erected, the days of miracles, when gods and monsters roamed the earth, when seas were parted, when oracles foretold the future, when miraculous beings and the resurrected dead mingled with ordinary men. After the House became occupied, he explained, as it gained strength and became more efficient, more attuned to its purpose, those “leaks” were plugged, all access to the Other Side was sealed off.

“Nothing is perfect,” the assistant said. “And, in the past, isolated spirits have made it through. But the House was built to maintain the laws of reason and rationality, and those exceptions had no influence or bearing upon that purpose. The Other Side was eventually forgotten about, passing into the realm of myth and fiction, and the occasionally sighted monster, the occasional haunted house, the occasional ghost became an aberration, entertainment, a story that was interesting but not to be believed.