Mark Sullivan

Whitney Burke is a renowned cave researcher and marine biologist who has abandoned her livelihood after losing an assistant in a tragic accident below ground. Though Whitney vows never to enter Labyrinth Cave again, her husband and daughter join a NASA-sponsored caving expedition.

When the expedition is overtaken by a group of criminals, Whitney must overcome her paralyzing fear to save her husband Tom, her daughter Cricket and, ultimately, herself.

A driving narrative that features the terrifying subterranean atmosphere of caves, a range of fascinating characters, and heart-stopping action sequences, the reader is dropped into the story with force and momentum in this astounding tale of adventure.

The Accident

In the northwest corner of Alabama, Ayers Ridge rises fifteen hundred feet off a lime jungle of a valley all choked with kudzu. A muddy river called the Washoo rolls toward Ayers Ridge from the east, then disappears under the razorback for several miles before popping up on the other side and continuing its torpid course toward the Gulf of Mexico. Ayers is four miles long, a half mile wide at its base and lies near the geographical center of a region known as TAG, short for the Tennessee-Alabama-Georgia karst country, an area that contains some of the most formidable pit caves in North America.

High on the side of Ayers there is a bench cut into the hillside by thousands of years of wind and rain. There, in the dappled early morning light, the forest gave way to a gaping hole in the ground some twenty-five feet across. A darkened pit. The entrance to another world with the absurdly melodramatic name of "The Terror Hole."

Fog steamed out of Terror Hole cave. Fog blackened the oaks that clung to ledges above it's entrance. Fog turned the red soil on the pit's mantle as treacherous as watered ice. It was more than three hundred feet to the bottom.

On that slick mantle, a woman was maneuvering her way across with the concentrated agility of a city cat that has crept out an apartment window onto the narrow ledge of the thirtieth floor. She wore a yellow jumpsuit, a red helmet with headlamp and a red waist harness. A small red pack was slung bandoleer-style across her left shoulder and cinched at her right hip by a waist belt.

She rocked her ankles into the slope so her boot treads bit the mud, then eased her way out over the exposed tree roots, focused, confident and yet all too aware of how close she worked to the lip of the hole. One misstep and she would suffer a four-and-half second fall. Certain death.

But Whitney Burke was never one to focus on negative possibilities. She embraced the positive at every moment, a general state of cheeriness that only added to her beauty. She was athletically built and freckle-faced, with vivid emerald eyes, natural crimson lips, a bit too much nose, a narrow, dimpled chin and a funny left ear that folded over at the top. Framing it all was a thick mane of strawberry blond hair, one troublesome lock of which was always falling in her eyes.

Whitney scrambled the last few tricky feet to a rope lashed to one of the oaks. The line disappeared over the rim into the mist. She straddled the line and began the complicated task of rigging herself to it, then called into the depths: "ON ROPE!"

"On rope!" answers another woman's voice from somewhere far below.

With a quick flick of her wrist Whitney turned on her headlamp. She glanced back into the abyss and grinned in anticipation of the adrenaline rush that always accompanied her going over the edge in what cavers call a "pit drop." Then she recited a cautionary principal her husband, Tom, taught her years ago: Never give the cave a chance.

"ON RAPPEL!" Whitney yelled.

"On rappel!" the other woman hollered back.

Whitney had dropped down ropes into scores of such shafts in the past. Still her heart beat faster. But that, she knew, was a good thing; it meant she understood the consequences of her actions. The experts she had known who died caving became accustomed to the danger, grew dull in their perceptions, gave the cave a chance.

Whitney created slack on the rope in order to arch her body backward until it was almost horizontal above the three hundred foot hole. Then she squatted, blew out all her breath out in a burst and kicked free. She dropped ten feet before the stiff soles of her leather boots contacted rock again.

Luscious ferns sprouted from the bridle gray ledges around her. Small white flowers with magenta seeds grew from cracks in the wall. The place smelled like freshly-crushed nutmeg. She made a second kick and dropped another ten feet and a third ten. She bounced off the wall a fourth time and dropped into the cave's expanse where the walls became underhung, and she could no longer maintain contact with the rock.

Whitney slowed herself to a stop and leaned back, twisting lazily in space. The morning sun beamed angularly into the top of the shaft, cutting through the swirling mist, creating clouds of rose-tinted glitter. Her mouth hung agape and she yelled, "God, I love this! Where's my camera when I need it?"

"Down here, where you should be by now!" the woman below answered.

High in the Alabama sky, a small cloud passed into view. Whitney's delighted expression sobered as she inspected it. A powerful spring storm, not uncommon in this part of the south, could flood the lower reaches of the cave. But she had searched the web on her laptop only moments before leaving her truck. The latest forecast called for blue skies with occasional fair weather clouds.

Whitney dropped her chin and eased the tension on her rappelling rack, a rectangular metal device, the bars of which interlaced with her rope. She began to slide, spinning round and round in long, descending spirals that allow her a panoramic view of the cave's interior. Narrow limpid waterfalls plunged fifty feet, splattered off rock outcroppings, then plunged again and again in a series of shimmering cascades. Moss covered much of the pewter-colored rock, which appeared carved by the hand of genius.

Twelve seconds and one hundred feet down, the sunlight splintered into three shafts that shined weakly against the west wall of pit. The vegetation dwindled. At a half minute and two hundred feet, Whitney spun down the rope into what cavers call the twilight, and the fog cleared. At three hundred feet, Whitney shivered; the cave air was a constant fifty-six degrees and saturated with moisture. At twenty feet off the bottom, the walls below her turned brackish brown. Her headlamp revealed a floor littered with boulders, scree and moldering logs. In the left wall of the pit, a six-foot black slot-like opening in the left wall of the pit beckoned.

A young Asian woman stood next to the opening where Terror Hole cave went horizontal, adjusting the flame of a carbide lamp, the kind miners used to wear. Jeannie Yung was Whitney's research assistant. She was eight years Whitney's junior with flawless skin, shiny black hair and a constant expression of bemusement on her face.

"Fancy meeting you here!" Whitney said as her boots reached the floor.

"Well, it is the best place to meet confirmed troglobites," Jeannie replied, snapping her helmet in place. "And you know I have this thing for slimy blind creatures."

"Think they'll mind us crashing the party?"

"Are you kidding? They'll be thrilled to have a couple of babes like us show up."

Whitney laughed as Jeannie came across the wet stone to help her.

"Great ride, huh?" Jeannie asks.

Whitney leaned back to stare up at how, way, way up in the tube, the mist seemed to create a back-lit opaque ceiling separating the world above from the world below.

"Absolutely beautiful," she said, unfastening her rack from the rope, then unhitching her climbing harness.

"What do you figure for time inside?" Jeannie asked.

"Why you got a hot date?"

Jeannie blushed. "Well, Jim's coming in from Purdue for the weekend. I wanted to be at the Nashville airport by four."

Whitney smiled. Jeannie had been working for her nearly three years and was just a thesis away from her doctorate in environmental science. Her assistant was as devoted a young scientist as she has ever known, but, in Whitney's opinion, Jeannie paid too little attention to her personal life. A weekend with Jim was a step in the right direction.

"No problem," Whitney said. "I promised Cricket I'd be there for her track meet. We'll be in and out in four hours, tops. We might even have time for a salad at Hennesseys on the way north."

"Great," Jeannie said. "Now what do you say we go crash that crayfish orgy!"

Whitney was still laughing as she entered the slot in the wall of the pit.

Immediately, her visibility was reduced to the narrow cone of soft light cast by her headlamp. The Terror Hole's walls turned slick, close and mottled gray. Whitney's helmet bumped against the smooth ceiling and she slowed and cast her beam forward into inky darkness. The cave ahead was becoming smaller, tighter, wetter, a place saturated with the threat of claustrophobia.

For a second Whitney remembered just how tight the way ahead became, then she shrugged it off. Narrow places had forced her to deal with the phobia a thousand times before. The fear of being closed in never goes completely away, but it can usually be managed.

The ceiling dropped again. She and Jeannie got down on all fours and crawled their way deeper into the cave. One hundred yards further on, the floor disappeared into a chimney some twenty-feet deep and about half the width of an elevator-shaft. They descended by bracing their feet and backs against either wall and shimmy-sliding down.

At the bottom of the chimney, for nearly seventy-five yards, the cave became a twisting, muddy crawlway about twenty inches high. The tube was so tight that Whitney and Jeannie could not crawl; they had to lie on their sides and slither like snakes, pushing their packs along in front of them. It was exhausting work made worse by little nubs of rock that grabbed at their boots, ankles and kneepads, made them think for an instant that they had finally been thrust into every caver's worst nightmare -- getting stuck.

It took thirty minutes to negotiate the tube, then descend another fifteen-foot chimney and emerge into an oval-shaped passage. Water dripped off stalactites into an easy-flowing stream that ran down the center of the passage. Whitney and Jeannie moved down the rivulet looking for blind crayfish.

With two claws, a segmented tail and long antennae, the crayfish looked like lobsters. But their coloring was pale to the point of opacity. And their eyes were pupiless, like freshwater pearls set on either side of their beaks. At each pool where they found crayfish, the women inserted a triangular orange flag to mark the spot. They planned to return to the same lagoons in a week to count and observe the crayfish all over again.

Whitney was a marine biologist as well as a speleologist, a specialist in cave ecology. More specifically, she was an expert on how pollution, especially agricultural pollution, affected rivers and cave life. She wrote her Ph.D. thesis on the ecology of subterranean rivers. She believed the delicate health of such ecosystems were as much an indicator of man's effect on Earth's environment as the size of the hole in the ionosphere above the South Pole. She and Jeannie were in the bottom of Terror Hole cave because this was the breeding season for cambarus aculambrum, blind crayfish, and they were trying to determine whether chemicals from irrigated fields upstream were disrupting the reproductive cycles of the endangered species.

After an hour of working their way along the underground stream, counting crayfish as they go, they reached a broad, shallow pool. Mud slicked the sides of the pool. Gravel and stones like polished marbles covered the bottom. On top of the stones, blind crayfish milled about.

"I count seven," Whitney said.

"Same here."

"Twenty eight pools. That's a solid sampling."

"I'm hungry."

"Me, too," Whitney replied. "Let's eat before we head out."

Jeannie nodded and slumped against the wall of the cave. Whitney took a seat on the other side of the pool against the wall opposite her assistant. She stowed her notes in a zip-lock bag, then fished in her pack for tins of boneless cooked chicken and fruit cocktail, a commercially-manufactured energy bar and a water bottle filled with Gatorade. As she ate, she let her light wander about the little grotto. More of those amber-colored stalactites clung to the ceiling. Beyond them, the passage drifted to the northeast, shrouded itself in gray, then disappeared into perpetual night.

Oddly, Whitney took solace from the solemn environment. She never got tired of being in caves. As her late father-in-law always used to say, "Where else can you go these days, other than the bottom of the sea or another planet, where you have the chance to walk where no human has been before?"

That notion caused Whitney to think about Tom. She and her husband had planned an evening out after Cricket's track meet. Whitney remembered the black negligee she bought on impulse the other day. She imagined herself appearing before Tom wearing it and couldn't help but grin.

"Hey, check this out," Jeannie said, breaking Whitney from her thoughts. Her assistant was on her hands and knees, the flame of her carbide lamp inches above the surface of the pool.

"What's going on?" Whitney asked.

Jeannie looked up, puzzled, worried. "I've never seen the trogs act like this."

Whitney aimed her headlight at the placid cave lagoon. Twenty minutes before the crayfish had been gathered at the pool's center. Now three of them crawled at a frantic clip across the streambed. Two were already at the banks clawing into the smooth brown muck of the pool's bank.

For a moment, Whitney seemed suspended. No future. No past. Sheer inertia. Then she felt disbelief followed by gut-wrenching horror. A blind crayfish is usually as active as a tortoise. One of their odd characteristics is that they will bury themselves in mud. They do it to survive being washed away in the rushing waters of early spring. Even then their pace is sluggish. These crayfish were acting as if they sensed a tidal wave roaring at them.

"Oh, Jesus, no," Whitney whispered.

"What?" Jeannie demanded. "Why are they doing that?"

"Flash flood!" Whitney cried, leaping across the pool, going for her gear.

Jeannie dove to her knees and shoved things into her pack, muttering, "Fucking weathermen! Fucking weathermen!"

In less than thirty seconds, both women were tightening their packs into position. Then they heard it: a distant, guttural shoofing noise. Somewhere outside the ridge, the Washoo, the surface river into which the underground stream flowed, was breaching its banks and backing up into its tributaries.

"Run!" Whitney screamed.

Their headlamps sliced the gloom as they tore back down the passage toward the chimneys. Their footfalls splashed against the sound curtain of water rising behind them. Two hundred yards down the passage a mound of sediment blocked their way and they had to crawl around it. The handprints and knee prints they left in the sand earlier in the day were almost washed away. "It's up four inches!" Jeannie shouted.

They scrambled up the bank and raced on. In fifteen minutes they reached the bottom of the first chimney. The water in the channel was up eleven inches.

Whitney grabbed at a crack in the wall, hoisted herself up into the chimney and started to climb.

"C'mon," Jeannie urged. "C'mon."

"I'm going as fast as I can."

"It's up twenty inches," Jeannie yelled after her. "We're ten minutes from pipe full. I'm not waiting for you to clear. I'm coming up."

"Do it," Whitney said, then clenched her jaw and forced herself to go faster, to try not to focus on the extraordinary pace at which the water was rising.

But it did not make sense. For Terror Hole cave to flood this fast, the storm outside had to be a deluge of at least five inches an hour and it had to have been raining that way from the moment they entered the first horizontal shaft of the cave. Impossible. She checked the meteorological data herself. But there was no denying the facts -- this was a hundred year flood, maybe a thousand-year flood. And she and Jeannie were in the worst possible place to survive it.

Whitney reached the top of the chimney with Jeannie right behind her.

"You think it can come up and flood the next level?" Jeannie panted. The water boiling up into the chimney below them had a reddish tint. The lower passage in which they counted crayfish was pipe-full, flooded to a sump.

"We're not waiting around to find out," Whitney said.

With that she ripped off her pack and darted into the two hundred and twenty-five foot crawlway. At the far end opened a second chimney, the way to higher ground. They got on their sides and dragged themselves into the tube. The cave floor was ridged like thousands of scallop shells, which clawed at their clothes and boots.

After fifteen minutes dragging herself across the scalloped floor, Whitney collapsed and lay gasping on her side. Sweat gushed off her brow, seeped into her eyes, stung and turned the world a hazy yellow. "Give me a sec."

Jeannie was still right behind her, puffing hard. "Take a minute," she said. "We're a third of the way there already. We're gonna make it."

There, some hundred feet down the crawlway, the cave roof was barely four inches over their heads and the walls pressed in a mere six inches from their torsos. The headlamp light in that confined place seemed hypnotic. Whitney stared into the light and realized that she let her daughter, Cricket, go to sleep last night without telling her she loved her. And Tom had been away at meetings in Houston all week; they'd barely spoken.

Then Whitney noticed something out of the corner of her eye, something that erased all thoughts of family and home. There were two of those scallops shell formations on the floor right in front of her. Muddy dollops of water fill each of the stone divots, which were separated by a single fringe of limestone. The water in the rearward scallop was lapping hard against the rock separation.

"Jeannie, are you moving back there?" Whitney demanded.

"Moving?" Jeannie replied, still breathless. "Give me a break."

Whitney looked back to the cave floor. The two pools had become one now, a pool that was eating up the bottom of the crawlspace with every second that passed.

"It's in the tube!" she screamed.

"For god's sake go!" Jeannie shrieked. "Go!"…

Whitney battled the hysteria surging within her and by sheer will pulled herself along. But with every foot of passage gained, she felt the power of something wild, savage and uncontrollable take possession of her. She had the overwhelming desire to get up somehow and run, wanting nothing more than to smash at the walls of her confinement and escape into sweet, clean, open air.

Whitney reached a section of the cave that dog-legged left and then immediately back to the right. The water was six inches deep now. Her hands and forearms were totally submerged. A foot of air remained. Whitney made it through the contortion, glanced up and saw what looked like the arched interior of a belltower about three feet wide and ten feet high. She ducked down to tell Jeannie. The crown of her assistant's white helmet poked around the second dog-leg.

"There's a shaft ahead," Whitney called, "with a ledge that should get us above flood level."

Jeannie squirmed forward a foot, stopped, then splashed, wheezed and pulled herself along another ten inches. Suddenly her eyes widened and widened again. "Whitney, I'm caught!"

Whitney jerked at the dread that swept over her. "Where?"

"My left boot. It's locked in a crack in the floor!"

Jeannie's face turned crimson as she struggled to free herself, then she stopped and heaved in frustration. Water reached the corner of her mouth and she sputtered at it.

"Try to go backwards," Whitney soothed. "Caving 101, remember? Whatever you can get into, you can get out of."

Jeannie nodded. She braced her hands against the ceiling and pushed, arching her body in a grotesque limbo move. She strained, let out a grunt of exertion, strained again, then all at once she let herself slump. "No way! No way."

"I'm coming in there!"

Whitney stood into the belltower grotto. She threw her pack up onto the little ledge, then ducked back into the lower passage. Jeannie had twisted her face toward the ceiling to keep her mouth out of the water. The flame of her carbide lamp burned a black tongue on the roof of the passage. Whitney reached Jeannie in three pulls, got her hands against her assistant's shoulder and said, "I'll push on three, okay?"

Jeannie seemed not to hear. She stared at the black tongue her lamp scorched on the roof of the cave passage.

"On three!" Whitney yelled.


"One, two, three!"

Whitney got her left hand against Jeannie's shoulder and pressed forward with all the strength she could muster. She felt the muscles in her assistant's upper body bunch for the longest time and then sag again. "It's no good," Jeannie said.

They rested helmets against each other a second, panting, watching the water swirl in the glow of their lamps. Then Jeannie started to cry. "Whitney, I'm so scared."

Whitney fought off the urge to sob, too. She thought of her young daughter, sitting in school, and her husband, on his way home from a meeting in Houston. Then she gazed into Jeannie's eyes. Over the past few years they had become fast friends, the sisters neither of them ever had.

"I'm gonna try one more thing, okay?"

"Okay," Jeannie whimpered.

"When I tell you to, you're going to arch your body as high as you can against the ceiling, I'm going to try to get under you and see if I can untie your boot. Ready?"

Jeannie trembled, but managed to nod.

Whitney took a big breath and dropped into the water. With the powerful light of her headlamp it was all harshly bright and bubbling brown. Then she found Jeannie's coverall and got a shoulder under her assistant's torso and reached as far as she can. Her fingers brushed Jeannie's thigh, her knee, her shinbone … Whitney struggled, shifted and stretched again. Her lungs felt as if a torch was being lit inside them.

She breached back up. "I can't reach it. I…"

The water pressed against their lips. Jeannie stared at Whitney. "Save yourself," she said finally.

"No, I won't leave you."

"For Tom and Cricket. You do it for them. You hear me?"

It was all beyond her comprehension, but Whitney knew she had to leave or they would both drown. Robotically, she backed out of the passage. Jeannie bent her head back to keep her mouth and headlamp flame above water. When there was only an inch of air left, she called out, "Tell my mom and dad and …Jim … that I loved them."

"Oh, God, Jeannie, I …"

But Jeannie Yung's flame was gone already, swallowed by the flood.

Whitney gaped at the copper water rolling at her, then hysterical climbed up into the belltower and onto the ledge where her pack lay.

Her headlamp revealed muddy water that swirled and rose below her, flooding more of the cave with every passing moment. She pressed herself back against the underground wall, trying to get away, but the water kept surging toward the ledge.

Then it stilled for a moment, followed by a sudden bubbling in the eddying copper current, as if a large obstruction somewhere downstream has dislodged. The water came up four quick inches. Then up breached the body, face down, bobbing.

Whitney moaned as the corpse bumped against her boots. She began to shake so hard she felt her purchase on the cave ledge weaken. She slid and plunged into the chill water next to the body. Her light flared then dims. She clawed at the dim rock over head, trying to get back up on the outcropping, trying to get away from the body. The body bobbed against her, then rolled over.

Whitney screamed in abject terror because the drowned figure was not her assistant, Jeannie, but her husband, Tom.
“Expertly crafted, [Labyrinth] is one of the most exciting yarns of this millennium. Brilliantly told and realized. A great read.”
-Publisher's Weekly (starred review)
Looked at in cross-section, the cave was a series of stacked hourglasses. We were in the upper-most chamber, backs pressed against one mud-slick wall, feet jammed against another, our butts hanging in space over a chasm that fell away twenty-five feet through jagged limestone teeth to a rushing cataract. As we moved sideways through that treacherous passage, the mud avalanched.

We were hours inside the Mammoth Cave complex of central Kentucky, negotiating the connection route between Salts and Unknown Caves. Well, everyone else was negotiating. I was just trying to survive the ordeal, telling myself it was all for the good of the story.

I take pride in the fact that many of my books are based on research in which I have immersed myself in an unfamiliar culture. To write "The Fall Line," I lived and skied with extreme skiers in the Sierras and the Rockies. To research "The Purification Ceremony," I apprenticed under expert deer trackers and spent months traversing remote forests in Maine, Montana and Alberta.

But nothing I'd ever done prepared me for the unforgiving world of hardcore caving, the subject of Labyrinth. Indeed, when I set out four years ago to write a thriller set underground, the extent of my caving experience was a two hour tour inside Mammoth when I was ten years old. Somewhere on the tour, I saw a real caver -- filthy, tough, wearing a helmet fitted with an old miner's lamp -- crawling out of what seemed an impossibly narrow passage. That image seared itself in my brain and nagged at me for nearly thirty years. Whenever I thought about that scene, I got nervous and excited.

For a mystery-suspense writer anything that provokes those sensations is fertile ground. So finally, a week before my fortieth birthday, I set out to become a caver. Luckily, I stumbled onto the fact that Roger Brucker, founding director of the Cave Research Foundation and author of many books, including "The Longest Cave," teaches a course in subterranean exploration at Mammoth Cave. I signed up.

I arrived at the cave research center one sultry afternoon in mid June with a brand new helmet, headlamp, cave suit and pack and, frankly, no idea what I was getting myself into. Eleven others had signed up for the course. All of them professed years of caving experience and were looking to go to the next level.

"I want to go where no man has before," Marty Brown told me "I want to find my own cave and explore it."

Brown's motivation, one I heard again and again among hardcore cavers during my research, became one of the central themes of Labyrinth. Indeed, I came to think of cave explorers as similar in psyche to astronauts, adventurers willing to take tremendous physical risks to be the first, to walk where no man has before. They're also sticklers about the technical aspects of their avocation.

"Too many novels about caves are flawed from a technical point of view," Brucker told me shortly after I arrived at Mammoth. "The authors just don't understand how caves and cavers work."

Of course, I did not have a full appreciation for what Brucker was saying when I showed up for his course. Nor did I understand how intense the experience of deep caving could be.

I figured that one out the next morning when we entered Unknown Cave through the famous Austin Entrance. Brucker was sixty-nine at the time, but once we were underground, he moved like a man in his twenties. I had to struggle to keep up with him. For hours we moved deeper into the cave while Brucker taught us how to read the scalloping on the walls as a guide to how the passages formed and where new ones might be found.

We crawled up narrow ladders through holes in the cave roofs, then free-climbed a massive "breakdown pile," debris from a roof collapse tens of thousands of years ago. We were six or seven miles from the entrance at that point and I was about to get another lesson about the nature of hardcore cavers.

One member of our group, whom I'll call Sally, had assured everyone that she'd had a great deal of experience caving. But it was soon apparent that she was in over her head physically and mentally. At the bottom of the breakdown pile, she collapsed and said she could not go on. Brucker sent us back toward the surface with his wife, Lynn. We exited the cave in the pitch dark after ten punishing hours underground. While Lynn went back in to help Brucker bring Sally out, the rest of the group took a vote not to let her go back in the cave during the rest of the week's trips. Later, after Sally emerged from the cave virtually delirious, I asked why.

C. Phillip Henry, a long-time caver from Ohio, looked me straight in the eye and said, "She couldn't have just gotten herself killed, she could have gotten us all killed. In this type of situation you have to be able to rely on the people you're caving with." The issue of self-reliance would become another major theme of Labyrinth.

The rest of the week was even more grueling. The third day of the course we learned how to negotiate the connections between cave systems. We began at eight in the morning with a forced march through Colossal Cave heading toward Salts Cavern. We were soaking wet most of the time. My body became scrimshawed with bruises. It was most brutal in the connection routes, which I came to describe as slithering down a sewer pipe lined with barbed wire.

We dropped down vertical drains, then waded and crawled through water to get to Salts. Much later that day, after exploring the interior of Salts Cave we connected back into the Unknown system once again. That route was an adventure I'll never forget as long as I live. We endured mud avalanches, then slithered and yanked our way across sharp scallops for nearly three hours before bellying one by one under “Guillotine Rock,”which, as the name suggests, would have crushed us if we'd dislodged the little rock that held the massive boulder up.

"The vast majority of cavers have never gone through a connection route and now you've done two in one day," Brucker said after we staggered out of Unknown fifteen hours after we'd entered Colossal. "You guys have what it takes. To be a cave explorer you have to be willing to go underground for long, long periods with little rest and you have to be willing and eager to go down the drains. That's the only way to find big cave."

I would go on to learn dozens of other lessons the other hardcore cavers who took me under their wing while researching Labyrinth. I would study rope techniques with Bruce Smith and Allen Padgett and rappel into cave pits in Tennessee and Alabama. I'd enter ice caves in Vermont and learn about methods of cave rescue. In the end, however, it was the initial awesome experience of following Brucker through the largest cave in the world that influenced every moment in the novel.