Past the threshold, our flashlights revealed dead pill bugs on the concrete steps, some crushed and some as whole and round as buckshot.

There were also the impressions of shoes and paws in the dust. These overlaid tracks were both ascending and descending.

“Me and Orson,” I said, identifying the prints. “From previous visits.”

“What’s below?”

“Three subterranean levels, each bigger than the hangar itself.”

“Massive.”

“Mucho.”

“What did they do down there?”

“Bad stuff.”

“Don’t get so technical on me.”

The maze of corridors and rooms under the hangar has been stripped to the bare concrete. Even the air-filtration, plumbing, and electrical systems have been torn out: every length of duct, every pipe, every wire and switch. Many structures in Wyvern remain untouched by salvagers. Usually, wherever salvage was pursued, the operation was conducted with an eye for the most valuable items that could be removed with the least effort. The hallways and rooms under this hangar, however, were scraped out so thoroughly that you might suspect this was a crime scene from which the guilty made a Herculean effort to eradicate every possible clue.

As we descended the stairs side by side, a flat metallic echo of my voice bounced immediately back to me at some points, while at other places the walls absorbed my words as effectively as the acoustical material that lines the broadcasting booth from which Sasha spins night music at KBAY.

I said, “They scoured away virtually every trace of what they were doing here—every trace but one—and I don’t think they were just concerned about protecting national security. I think…it’s just a feeling, but judging by the way they totally gutted these three floors, I sense they were afraid of what happened here…but not just afraid. Ashamed of it, too.”

“Were these some of the genetic labs?”

“Can’t have been. That requires absolute biological isolation.”

“So?”

“There would be decontamination chambers everywhere—between suites of labs, at every elevator entrance, at every exit from the stairwell. Those spaces would still be identifiable for what they were, even after everything was torn out of them.”

“You have a knack for this detective crap,” Bobby said as we reached the bottom of the second flight of steps and kept going.

“Awesomely smooth deductive reasoning,” I admitted.

“Maybe I could be your Watson.”

“Nancy Drew didn’t work with Watson. That was Holmes.”

“Who was Nancy’s right-hand dude?” Bobby wondered.

“Don’t think she had one. Nancy was a lone wolfette.”

“One tough bitch, huh?”

“That’s me,” I said. “There’s only one room down here that might have been a decon chamber…and it’s full-on weird. You’ll see.”

We didn’t speak further as we proceeded to the deepest of the three subterranean levels. The only sounds were the soft scrape of our rubber shoe soles on the concrete and the crunch of dead pill bugs.

In spite of the pistol-grip shotgun he carried, Bobby’s relaxed demeanor and the easy grace with which he descended the stairs would have convinced anyone else that he was carefree. To some degree, he was enjoying himself. Bobby pretty much always enjoys himself, in all but the most extreme situations. But I’d known him so long that I—and perhaps only I—could tell that he was not, at this moment, free of care. If he was humming a song in his mind, it was moodier than a Jimmy Buffett tune.

Until a month ago, I hadn’t been aware that Bobby Halloway—Huck Finn without the angst—could be either rattled or spooked. Recent events had revealed that even this natural-born Zen master’s heart rate could occasionally exceed fifty-eight beats per minute.

I wasn’t surprised by his edginess, because the stairwell was sufficiently cheerless and oppressive to give the heebie-jeebies to a Prozac-popping nun with an attitude as sweet as marzipan. Concrete ceiling, concrete walls, concrete steps. An iron pipe, painted black and fixed to one wall, served as a handrail. The dense air itself seemed to be turning to concrete, for it was cold, thick, and dry with the scent of lime that leached from the walls. Every surface absorbed more light than it reflected, and so in spite of our two flashlights, we wound downward in gloom, like medieval monks on our way to say prayers for the souls of dead brethren in the catacombs under a monastery.

The atmosphere would have been improved even by a single sign featuring a skull and crossbones above huge red letters warning of deadly levels of radioactivity. Or at least some gaily arranged rat bones.

The final basement in this facility—where no dust has yet settled and no pill bugs have ventured—has a peculiar floor plan, beginning with a wide corridor, in the form of an elongated oval, that extends around the entire perimeter, rather like a racetrack. A series of rooms, of different widths but identical depths, open off one side of this corridor—occupying the infield of the track—and through some of them you can reach a second oval corridor, which is concentric with the first; not as wide or as long as the first, it is nonetheless enormous. This smaller racetrack rings a single central chamber: the egg room.

The smaller corridor dead-ends at a connecting module through which you can enter the innermost sanctum. This transitional space is a ten-foot-square chamber accessed through a circular portal five feet in diameter. Inside this cubicle, to the left, another circular portal of the same size leads into the egg room. I believe these two openings were once fitted with formidable steel hatches, like those in the bulkheads between watertight compartments in a submarine or like bank-vault doors, and that this connecting module was, in fact, an airlock.

Although I am certain that these were not biological-research labs, one of the functions of the airlock might have been to prevent bacteria, spores, dust, and other contaminants from being carried into or out of the chamber that I call the egg room. Perhaps those personnel going to and from that inner sanctum were subjected to powerful sprays of sterilizing solution as well as to microbe-killing spectrums of ultraviolet radiation.

My hunch, however, is that the egg room was pressurized and that this airlock served the same purpose as one aboard a spaceship. Or perhaps it functioned as a decompression chamber of the type deep-sea divers resort to when at risk of the bends.

In any event, this transitional chamber was designed either to prevent something from getting into the egg room—or to prevent something from getting out.

Standing in the airlock with Bobby, I trained my flashlight on the raised, curved threshold of the inner portal and swept it around the entire rim of this aperture to reveal the thickness of the egg-room wall: five feet of poured-in-place, steel-reinforced concrete. The entryway is so deep, in fact, that it is essentially a five-foot-long tunnel.

Bobby whistled softly. “Bunker architecture.”

“No question, it’s a containment vessel. Meant to restrain something.”

“Like what?”

I shrugged. “Sometimes gifts are left for me here.”

“Gifts? You found that cap here, right? Mystery Train?”

“Yeah. It was on the floor, dead center of the egg room. I don’t think I found it, exactly. I think it was left there to be found, which is different. And on another night, while I was in the next room, someone left a photograph of my mother here in the airlock.”

“Airlock?”

“Doesn’t it seem like one?”

He nodded. “So who left the photo?”

“I don’t know. But Orson was with me at the time, and he didn’t realize someone had entered this space behind us.”

“And he’s got the nose of noses.”

Warily, Bobby directed his flashlight through the first circular hatchway, into the corridor along which we had just come. It was still deserted.

I went through the inner portal, the short tunnel, crouching because only someone under five feet could pass this way without stooping.

Bobby followed me into the egg room, and for the first time in our seventeen years of friendship, I saw him stricken with awe. He turned slowly in a circle, sweeping his flashlight across the walls, and though he tried to speak, he couldn’t initially produce a sound.

This ovoid chamber is a hundred twenty feet long and slightly less than sixty feet in diameter at its widest point, tapering toward each end. The walls, ceiling, and floor are curved to form a single continuous plane, so you seem to be standing in the empty shell of an enormous egg.

All surfaces are coated in a milky, vaguely golden, translucent substance that, judging by the profile around the entry hatchway, is nearly three inches thick and is bonded so securely to the concrete that the two appear to be fused.

The beams of our flashlights shimmered over this highly polished coating, but they also penetrated the exotic material, quivering and flickering to the depths of it, flaring off whorls of glittering golden dust that were suspended like miniature galaxies within. The substance was highly refractive, but light did not shatter through it in hard prismatic lines as it might through crystal; rather, buttery bright currents, as warm and sinuous as candle flames seduced by a draft, flowed and rippled through the thick, glossy surface plating, imparting to it the appearance of a liquid, purling away from us into the farther, darker corners of the room, there to dissipate like pulses of heat lightning behind summer thunderheads. Gazing down at the floor, I could almost believe that I was standing on a pool of pale-amber oil.

Marveling at the unearthly beauty of this spectacle, Bobby walked farther into the room.

Although this lustrous material appears to be as slick as wet porcelain, it is not at all slippery. In fact, at times—but not always—the floor seems to grip at your feet, as if it is gluey or exerts a mild magnetic attraction even on objects that contain no iron.

“Strike it,” I said softly.

My words spiraled along the walls and ceiling and floor, and a cascade of whispery echoes returned to my ears from more than one direction.

Bobby blinked at me.

“Go ahead. Go on. With the barrel of the shotgun,” I prompted. “Strike it.”

“It’s glass,” Bobby protested.

The extended sibilant at the end of his second word returned to us in a wash of echoes as susurrant as gently foaming surf.

“If it’s glass, it’s not breakable.”

Hesitantly, he gave the floor near his feet a gentle tap with the muzzle of the shotgun.

A quiet ringing, like chimes, seemed to arise simultaneously from every corner of the huge chamber, then faded into a silence that was curiously pregnant with suspense, as if the bells had announced the approach of some power or person of great import.

“Harder,” I said.

When he rapped the steel barrel harder against the floor, the ringing was louder and of a different character, like that of tubular bells: euphonious, charming, yet as strange as any music that might be performed on a world at some far end of the universe.

As the sound drained into another suspenseful silence, Bobby squatted in order to smooth one hand across the floor where he had rapped the shotgun barrel.

“Not chipped.”

I said, “You can bang on it with a hammer, scrape at it with a file, chop at it with an ice pick, and you won’t leave the slightest scratch.”

“You tried all that?”

“And a hand drill.”

“You’re a destructive imp.”

“It runs in my family.”

Pressing his hand to the floor at a few different points around him, Bobby said, “It’s slightly warm.”

Even on hot summer nights, the deep concrete structures of Fort Wyvern are as cool as caverns, cool enough to serve as wine cellars, and the chill sinks deeper into your bones the longer you haunt these places. All other surfaces within these warrens, other than those in this ovoid room, are cold to the touch.

“The stuff is always warm,” I said, “yet the room itself isn’t warm, as if the heat doesn’t translate to the air. And I don’t see how this material could retain heat more than eighteen months after they abandoned this place.”

“You can almost feel…an energy in it.”

“There’s no electrical power here, no gas. No furnaces, no boilers, no generators, no machinery. All stripped away.”

Bobby rose from a squat and walked deeper into the chamber, playing his flashlight over the floor, walls, and ceiling.

Even with two flashlights and the unusually high refractivity of the mysterious material, shadows ruled the room. Tracers, blooms, girandoles, pinwheels, lady ferns, and fireflies of light swarmed across the curving surfaces, mostly in shades of gold and yellow but some red and others sapphire, fading to oblivion in far dark corners, like fireworks licked up and swallowed by a night sky, dazzling but illuminating little.

Bobby said wonderingly, “It’s as big as a concert hall.”

“Not really. But it seems even bigger than it is because of how every surface curves away from you.”

As I spoke, a change occurred in the acoustics of the chamber. The whispery echoes of my words faded away, swiftly became inaudible, and then my words themselves diminished in volume. The air felt as if it had thickened, transmitting sound less efficiently than before.

“What’s happening?” Bobby asked, and his voice, too, sounded suppressed, muffled, as though he were speaking from the other end of a bad telephone connection.

“I don’t know.” Although I raised my voice almost to a shout, it remained muffled, precisely as loud as when I’d spoken in a normal tone.

I would have thought I was imagining the increased density of the air if I hadn’t suddenly begun experiencing difficulty breathing. Although not suffocating, I was afflicted severely enough to have to concentrate to draw and expel breath. I was swallowing reflexively with each inhalation; the air was virtually a liquid that I had to force down. Indeed, I could feel it sliding along my throat like a drink of cold water. Each shallow breath felt heavy in my chest, as if it had more substance than ordinary air, as though my lungs were filling with fluid, and the moment I completed each inhalation, I was overwhelmed by a frantic urge to get this stuff out, to eject it, convinced that I was drowning in it, but each exhalation had to be forced, almost as if I were regurgitating.

Pressure.

In spite of my rising panic, I remained clearheaded enough to figure out that the air was not being alchemized into a liquid but that, instead, the air pressure was drastically increasing, as if the depth of the earth’s atmosphere above us were doubling, tripling, and pushing down on us with crushing force. My eardrums fluttered, my sinuses began to throb, I felt phantom fingertips pressing hard against my eyeballs, and at the end of each inhalation, my nostrils pinched shut.