“It’s okay, Bernie Kosar,” I say, patting his back.

Sam and I drop to the ground and lay on our stomachs, both staring across the small valley at the cave’s almost indiscernible entrance. It’s far larger than I’d imagined, probably twenty feet wide and tall, but also much better hidden. There’s something covering it, a net or a tarp maybe, making it blend in with its surroundings; you’d have to know it’s there to be able to see it.

“Perfect location,” Sam whispers.

“Totally.”

My nervousness quickly turns to full-blown terror. As mysterious as the cave is, one thing I know for sure is that there’ll be no shortage of things—weapons, beasts or traps—that could kill us. I could die within the next twenty minutes. And Sam could, too.

“Whose idea was this, anyway?” I ask.

Sam snorts. “Yours.”

“Well, I have some stupid ideas sometimes.”

“True, but we have to get your Chest somehow.”

“There’s so much in there that I don’t even know how to use yet . . . but maybe they do,” I say. Then something catches my eye.

“Look at the ground in front of the entrance,” I say, pointing to a smattering of dark objects by the cave’s entrance.

“At the rocks?”

“Those aren’t rocks. Those are dead animals,” I say.

Sam shakes his head. “Great,” he says.

I shouldn’t be surprised since Six told us about it, but the sight of them fills me with even more dread, which I didn’t think possible. My mind races.

“All right,” I say, sitting up. “There’s no time like the present.”

I kiss the top of Bernie Kosar’s head, then run my hand down the length of his back, hoping this won’t be the last time I ever see him. He tells me not to go, and I communicate back that I have to, no other choice. “You’re the best, BK. I love you, buddy.”

Then I stand. I take the bottom of my shirt in my right hand so I can remove the Xitharis from the bag without touching it.

Sam messes with the buttons on his digital watch, putting it in stopwatch mode. We won’t be able to read its face once we’re invisible, but when the hour is up, the watch will beep—though I imagine by then we’ll have figured it out.

“Ready?” I ask.

Together we take our first step, then a second, and then we’re hiking down the trail that may very well lead to our imminent doom. I turn around only once, when I’ve nearly reached the cave, and see Bernie Kosar staring at us.

Chapter Twenty-Nine

WE GET AS CLOSE TO THE CAVE AS WE CAN WITHOUT being seen, and we duck behind a tree. I place the Xitharis stone on the sticky side of a section of duct tape. Sam watches with his fingers pinched around his stopwatch.

“Ready?” I ask.

He nods. I press the Xitharis and the tape to the very bottom of my sternum. I vanish instantly and Sam hits the watch’s button, eliciting a soft digital beep. I snatch Sam’s hand, and together we lurch around the tree and speed to the cave. It’s all about the task at hand now, and with that in mind I’m no longer as nervous.

The cave is covered with a large camouflage tarp. We navigate through the graveyard of dead animals, being careful not to step on any, which is hard to do without the luxury of seeing your feet. There are no Mogs outside, and I hurry forward and flick the tarp aside a little too forcefully. Sam and I stumble in and four guards jump up from their seats and raise cylindrical cannons like the one that was held to my forehead that night in Florida. We stand as still as statues for a brief moment, and then quietly sneak past, hoping they’ll attribute the tarp’s sudden disturbance to the outside wind.

There’s a cool breeze coming from a ventilation system and the air is oddly fresh, which I hadn’t expected considering it’s laced with poisonous gas. The gray walls are polished smooth like flint; electrical conduit connects dim lights evenly spaced twenty feet apart.

We pass several more scouts and slither by undetected. The anxiety of the ticking clock racks us both with stress. We jog, we sprint, we tiptoe, we walk. And when the tunnel narrows and declines steadily, we sidestep down it. The cool air grows hot and stifling, and a crimson glow at the end of the tunnel comes into view. We shuffle towards it until finally reaching the cave’s beating heart.

The cavernous hall is far larger than I’d imagined based on Six’s description. A long, continuous ledge runs along the circular walls and spirals all the way, from top to bottom, giving the overall appearance of a beehive; and the place is every bit as busy as one, too—there are literally hundreds of Mogs in sight, crossing the precarious stone arched bridges, entering and exiting tunnels. The deep floor and the vast ceiling are separated by a half mile, and Sam and I are situated very close to the middle. Two massive pillars sprout up from the floor and reach all the way to the ceiling, keeping the whole thing from caving in. The number of passageways around us is endless.

“My God,” Sam whispers in awe, taking it all in. “It’d take months to explore this entire thing.”

My eyes are drawn to the lake of glowing green liquid down below. Even from so far away, the heat off of it makes it hard to breathe. But despite the near roasting temperatures, twenty to thirty Mogs work around it, retrieving carts full of the bubbling stuff and quickly taking it away. Past the green lake, my eyes focus on something else.

“I think we can pretty much guess what we’ll find down that tunnel with the giant bars,” I whisper. It’s three times the height and width of the passageway that carried us here, and a checkered pattern of heavy iron bars covers it, keeping caged whatever beasts are inside. We can hear them howl from below, deep and almost sorrowful. One thing is immediately clear: their numbers are far from few.

“It’ll literally take months,” Sam says again in a disbelieving whisper.

“Well, we have less than an hour,” I whisper back. “So we better hurry.”

“I think we can put a big X through all those dark narrow tunnels that look obstructed.”

“I agree. We should start with the one directly across from us,” I say, looking at what appears to be the central room’s main artery, wider and better lit than the others, the one with the greatest number of Mogs coming and going. The bridge over to it is just a long arch of solid rock that, at most, is two feet wide. “Think you can make it across that archway?”

“We’re about to find out,” Sam replies.

“Lead or follow?” I ask.

“Let me lead.”

Sam takes his first few steps uncertainly. Since we have to keep our hands locked, for the first forty feet or so we shuffle along sideways. It takes forever, and if we’re to get to the other side and back again, there’s no way we can do it at this pace.

“Just don’t look down,” I say to Sam.

“Don’t be cliché,” he responds, squaring his body. We move ahead slowly, and I wish I could see my feet for just this obstacle. I’m so focused on not falling that I don’t feel Sam stop ahead of me, which causes me to stumble into him, nearly knocking us both off the bridge.

“What are you doing?” I ask, my heart thudding in my chest. I look up and see why he’s stopped. Racing towards us is a Mogadorian soldier. He comes charging across in a jog, and he’s already so close there’s hardly time to react.

“There’s nowhere to go,” Sam says. The soldier continues forward, cradling a wrapped bundle in his arms, and when he’s close enough I feel Sam crouch. A second later, the Mog’s feet are swept out from under him, completely catching the soldier off guard. He falls over the side of the bridge and catches himself with one hand as the bundle he was carrying drops away. The Mog cries out in pain as my invisible foot crushes his fingers, and he lets go and drops through the air, splattering far below with a sickly thud.

Sam races us forward before any further calamities arise. Every single Mog in the area has stopped in midstride, staring at one another with confused expressions. I wonder if they believe what just happened was an accident, or if they’re now on alert.

Sam squeezes my hand in relief when we’ve made it across, and he lurches ahead, having gained a world of confidence from killing the soldier.

The next corridor is wide and busy, and it doesn’t take long for Sam and me to realize we’re heading in the wrong direction; the rooms we pass are exclusively private, and the entire wing seems to be where the Mogs live: caves with beds, a large open cafeteria with hundreds of tables, a shooting range. We rush down a nearby corridor, but the result is the same. And then we try a third.

We follow the winding tunnel deeper into the mountain. Several tributaries lead away from the main drag, and Sam and I randomly turn down them based on nothing more than gut feeling. Aside from the main hall we entered, the rest of the mountain is nothing more than an interconnected network of damp stone corridors, off of which various rooms house research centers with examination tables, computers and shiny, sharp instruments. We pass several scientific laboratories that we both wish we had the time to investigate further as we rush by. We’ve probably run a mile, maybe two, and with each new corridor that turns up nothing, stress floods my veins.

“We can’t have more than fifteen minutes left, John.”

“I’m aware of that,” I whisper, desperate and irritated and quickly losing hope.

When we take the next turn and rush up a steady incline, we pass the thing I’d feared most: a room full of prison cells. Sam stops in midstride and keeps a firm grip on my hand, causing me to stop as well. Twenty to thirty Mogadorians guard more than forty cells, all lined up in a row, with heavy steel doors. In front of each door, there’s a bubbling blue force field pulsing with electricity.

“Look at all those cells,” Sam says. I know he’s thinking of his dad.

“Wait a second,” I say, the solution flashing into my head from out of nowhere. It’s so obvious.

“What?” Sam asks.

“I know where the Chest is,” I say.

“Seriously?”

“So stupid of me,” I whisper. “Sam, if you could pick just one place in this entire hellhole where you’d absolutely refuse to go, where would that place be?”

“In the pit with the howling beasts,” he answers without a second’s hesitation.

“Exactly,” I say. “Come on, let’s go.”

I lead him back up the corridor that’ll empty out at the cave’s center; but before we’ve left the cells behind, a door clangs open and Sam jerks his hand to stop me.

“Look,” he says.

The nearest cell door stands wide-open. Two guards enter. They speak angrily for ten seconds in their native tongue, and when they exit they’re clutching the arms of a pale, emaciated man in his late twenties. He’s weak to the point of having trouble walking, and Sam’s grip tightens as the guards shove him forward. One of them unlocks a second door, and all three disappear through it.

“Who do you think they have locked up in there?” he asks as I pull him forward.