We didn’t speak again until we were past the buffalo herd and under the fringe of the lodgepole forest.

“Okay, guys,” I panted as I skated to a stop under the trees. “Let’s take a short breather.” My legs were shaking, and I felt giddy after coming so close to the buffalo herd, although I’d never admit that to Zeke and Colin.

“Good plan, Boss Lady,” said Zeke.

He pulled off his backpack and took out what looked like a chunk of Swiss cheese wrapped in tin foil. They he pulled out a dried salami, took a bite out of both, and handed them to Colin.

“You guys didn’t bring a knife for that?” I asked, raising an eyebrow.

“Why’d we need a knife for this?” Zeke asked around a mouthful of salami.

I shook my head and gave up yet another futile attempt to civilize my graduate students. When Colin handed the block of cheese to me, I tore a chunk off with my teeth.

“Don’t worry, Professor,” Colin said. “What happens in the backcountry, stays in the backcountry.”

Grinning, I felt a surge of gratitude so sudden, unexpected, and fierce it brought tears to my eyes. “Thank you,” I said, the words catching in my throat. “I’m glad you’re here.”

Colin shrugged. Zeke let out a tremendous belch.

“Let’s keep moving,” I said, zipping up my jacket. It felt colder under the trees.

Zeke frowned. “Isn’t, uh, Wolf Boy going to meet us? Or something?”

I sighed. “Okay, first, he has a name. It’s Vali, not Wolf Boy. And second, he’s not a wolf anymore.”

“And is Vali going to meet us?” Colin asked, gently. “To explain why the wolves are leaving Yellowstone?”

I glanced into the woods. They seemed dark, as if the trees were somehow swallowing the bright sunlight falling across the valley. The burnt scent was stronger now; I could sense it even with my eyes open.

“Can you smell that?” I asked, ignoring Colin’s question.

Zeke and Colin glanced at each other. They were silent long enough for me to worry they’d both decided their doctoral advisor had completely and totally lost her fucking mind. Then Colin nodded, and raised his arm.

“It’s coming from there,” he said, pointing into the trees. “And it’s getting stronger. We’re following it, aren’t we?”

My chest tightened. “I’m following it,” I said. “You don’t need to. I don’t know what it is, exactly, but it’s probably seriously dangerous. And no, Vali isn’t coming to us. I’m going to him.”

Zeke grinned. “Hey, Boss Lady, don’t worry about it. We’ve gotcha covered. And Wolf Boy, too.” He winked as he pulled his backpack off the snow and shrugged in onto his shoulders.

****

IT DIDN’T TAKE LONG for the forest to become strange. The trees grew tall and dense. Too dense. Yellowstone doesn’t get much rain, and the volcanic soil in this part of Montana is thin and nutrient poor. It’s not an ecosystem that can support dense vegetation. But those trees...

“I don’t even think these are lodgepole,” I said, pressing my mittened hand against the dark trunk of an enormous pine.

We’d stopped again to pick our way around a windfall of dead logs, which meant taking off our skis, climbing over tree trunks larger than any I’d ever seen in Montana, and then knocking the ice off our boots to put our skis back on. It was slow, cold, tedious travel. My calves spasmed with cramps, and my arms trembled with the effort of lifting my skis. Even my shoulders ached from pulling myself over fallen logs.

“No, they’re not lodgepole,” said Colin. His voice was soft and hushed in the darkness of the forest.

Zeke clambered over the tree trunk and stood next to us. “You think that’s weird,” he said. “Check this out.”

He unzipped his pocket and pulled out a small compass. I leaned toward him to look. The red compass needle ticked and swung wildly, making a full circle in his hand. It settled for a moment between E and S, skipped, and spun again. Colin whistled.

“You should go back,” I said. “You should both go back. Now.”

Zeke shook his head. “Are you kidding? This is the coolest shit I’ve ever seen. Colin, did you get a load of this?”

Colin nodded. “I don’t think this place is exactly normal.”

I knocked a clump of ice off the bottom of my ski boot and hesitated. My foot hovered in mid-air as I watched Colin and Zeke stare at the still-spinning compass needle. My chest ached. I was torn between telling them to get the hell away from here as fast as they could, or tearing up again as I thanked them for coming this far.

Colin met my eyes. “I think we should keep moving. This way, right?” Colin asked, raising a ski pole.

I nodded, my mouth dry. The scent was so strong now I could almost see it, like a dark haze hovering over the snowy ground, snaking between the massive trees. Shaking myself, I clicked my boot into my ski binding. By now I could have followed the scent blindfolded.

“I think we’re getting close,” I said.

I pushed my skis through a narrow gap between two pines so tall their crowns were lost in the gathering darkness. Beyond those pines was a meadow. The last of the day’s light was just fading from the periwinkle sky above the trees, leaving the clouds streaked with pink. Snow lay thin on the ground in the clearing, and there was another scent in the air, the low, sulfur tang of geothermal features.

On the other side of the meadow was the cave.

My heart hammered in my mouth as I turned around, wondering what I could possibly say to Zeke and Colin to explain that looming, dark maw. Zeke pulled himself through the trees and skidded to a stop next to me.

“Hey, sweet,” he said. “Hot springs!”

Of course. Now I noticed steam rising in the air like white ghosts against the darkness of the trees ringing the clearing. At least a dozen small, translucent blue pools, glimmered softly in the meadow. I heard the swish of skis on snow as Colin slid next to me.

“Huh,” Colin said, sniffing the air. “I’ve lost it.”

Zeke scratched his head. “Yeah, me too. You, Boss Lady?”

I stared past them at the mouth of the cave. The darkness inside the entrance seemed almost palpable, like a heavy oil slick, waiting to spill across the meadow.

“There,” I said. It came out a rough whisper; my voice had fled.

Colin and Zeke turned to the cave.

“Through those woods?” Colin asked. He raised his ski pole, jabbing it at the cave.

“You don’t see it?” I whispered.

Colin’s brow furrowed under his knit wool hat. “See what?”

I swallowed. “That cave,” I hissed. “That giant freaking cave!”

Just looking at the dark entrance made my skin crawl, but I was afraid to turn away. As if something might come out of that inky void the moment I turned my back.

“Cave?” Colin echoed. “I don’t see a cave.”

“All I see are more goddamn trees,” Zeke said.

A slow shiver ran the length of my spine. I’d wanted to send them away earlier, but I’d hesitated. Now I had no choice; that cave entrance must be for me alone.

“Then I guess you’re not coming with me any more,” I said, clearing my throat to hide the waver in my voice.

“Hey, I didn’t wanna give you the wrong impression,” Zeke said. “I mean, it’s more goddamn trees, but that’s not a problem. Hell, I love skiing through this creepy ass forest!”

“I know,” I said, smiling in spite of myself. “But I don’t think you can come any further. I think this next part is just for me.”

Colin shrugged. “Well, we can certainly try.”

“Sure. Of course you can,” I said.

I slid my backpack off my shoulders and let it rest against my skis, sighing with relief. For a second my entire body felt like it was floating. I clipped out of my skis and propped them against a tree, wedging my backpack between them. There wasn’t much snow on the ground between the opalescent, steaming pools, and I seriously doubted skis would be very useful against a dragon. Zeke and Colin watched me. Their eyes seemed wide in the fading light.

Squaring my shoulders, I turned to face the cave. It looked exactly like it had in my dream on Christmas Eve, when I saw Vali for the last time.

“No, it’s not quite right,” I muttered under my breath. I’d been standing slight closer to the entrance, and a little to the right.

I took a few steps to the right.

“That should be about right,” I whispered as I forced my eyes off the steam-dappled ground and back to the mouth of the cave.

The darkness in the mouth of the cave moved. It surged slightly, then lay still. As if it were breathing. As if it were waiting for me.

“Boss Lady?” Zeke’s voice sounded strange and far away.

I turned around, my heart hammering wildly against my chest. I’d left the meadow; I was already at the mouth of the cave. Zeke and Colin stood a good twenty yards away, beneath the trees, next to my skis and backpack. They seemed very far away, almost in another world.

My gut tightened, and my skin prickled with a long, slow shiver. From the corner of my eye, the darkness in the mouth of the cave shifted and undulated.

“Colin and Zeke,” I called, cupping my hands around my mouth to carry my voice. “Do not wait for me! You pack up, and you head home.”

Both of them shook their heads simultaneously. Insolent little shits, I thought.

“No,” Colin called. His voice echoed strangely in the clearing. “We’ll wait for you.”

Zeke pushed himself forward on his skis, and Colin followed. It seemed to take a very long time for them to cross the small meadow. Even when they stood almost next to me, Colin and Zeke still looked oddly distant and distorted. Like they were on one side of a mirror, and I was on the other.

“You, uh, need anything?” Zeke asked. He looked uncertain.

I had never, in four years, seen Zeke look uncertain about anything. The hesitant, caged expression on Zeke’s face terrified me even more than the shifting, churning darkness behind me, more than the spinning needle of the compass or the strange trees that didn’t fit the ecosystem or the low, acrid burnt smell in the air.

I shook my head. My hands trembled, and I tried to hide them behind my back. “I’m fine.”

“You want a ski pole?” Colin asked. It sounded like a joke, but his face was pale, and his lips were drawn tight.

“Bear spray?” Zeke offered.

I closed my eyes, remembering the enormous blue sword Vali had pulled from his back and swung in a wild, hissing arc before he entered the cave. I pictured myself swinging one of my thin, little white ski poles through the cold gloaming, and I couldn’t stop my laugh. Colin and Zeke looked even more concerned, and even further away, when I turned back.

“I don’t think it’s that kind of cave,” I said. “I’m going in. Please don’t wait for me.”

I turned from their pale faces and stepped into the darkness.

****

THERE WAS A SMALL, battery operated headlamp in my pocket. I fumbled in the darkness for a few seconds before I found the headlamp and pulled it over my forehead. For a brief second after I switched it on, the lamp flared, and I could almost make out my ski boots. Then it dimmed rapidly, until I couldn’t even see my hands. I pulled the headlamp off my head and examined it, seeing only a dim flicker of orange deep in the bulb. Then the darkness flowed over my hands, and that flicker was gone.

Damn. I stuffed the useless headlamp back in my pocket and started shuffling forward slowly, my arms raised so I didn’t crash into anything. The ground under my feet felt smooth and hard, almost like concrete, and it sloped gently downhill.

“Hello?” I whispered. My voice bounced and echoed in the darkness, amplifying until it seemed to be coming from everywhere.

Hello? Hello? Hello?

My skin crawled at the reverberating crash of my own voice. So much for subtlety.

I walked for a long time. Long enough to realized I was hungry and thirsty, in addition to cold and sore. Long enough to regret leaving my backpack with my skis. Slowly, I realized I could see the pale flash of my fingers in front of me. A few more steps, and I could see my white ski pants, and the dark, hard ground beneath me. A few more steps—

My breath caught in my throat. The hum of fluorescent lights and the beep and chirp of medical equipment rushed into the cold air of the cave. My nostrils filled with the harsh, sterile smell of bleach. The murmur of voices grew behind me. Three nurses wearing matching light blue scrubs emerged from the darkness and brushed past me, vanishing a few steps to my right.

“What the fuck?” I whispered.

I recognized those nurses; they worked in the Neonatal Intensive Care Unit at Chicago’s Children’s Hospital. And they were working the day—

I blinked and turned slowly, expecting to see the darkness of the cave behind me. No. I faced a blank, white wall and a massive bulletin board covered with reports, forms, and schedules. And a huge, impassive, white clock. Ticking down the seconds.

“Time of death,” said a man’s voice.

I turned again.