A single line of blood trickles down the pale underside of her arm, a red seam on a white sleeve.

At first, Alice thinks it's just a fly and takes no notice. Insects are an occupational hazard at a dig, and for some reason there are more flies higher up the mountain where she is working than at the main excavation site lower down. Then a drop of blood splashes onto her bare leg, exploding like a firework in the sky on Guy Fawkes night.

This time she does look and sees that the cut on the inside of her elbow has opened again. It's a deep wound, which doesn't want to heal. She sighs and pushes the plaster and lint dressing tighter against her skin. Then, since there's no one around to see, she licks the red smear from her wrist. Strands of hair, the color of soft brown sugar, have come loose from under her cap. She tucks them behind her ears and wipes her forehead with her handkerchief, before twisting her ponytail back into a tight knot at the nape of her neck.

Her concentration broken, Alice stands up and stretches her slim legs, lightly tanned by the sun. Dressed in cut-off denim shorts, a tight white sleeveless T-shirt and cap, she looks little more than a teenager. She used to mind.Now, as she gets older, she sees the advantage of looking younger than her years. The only touches of glamour are her delicate silver earrings, in the shape of stars, which glint like sequins.

Alice unscrews the top of her water bottle. It's warm, but she's too thirsty to care and drinks it down in great gulps. Below, the heat haze shimmers above the dented tarmac of the road. Above her, the sky is an endless blue. The cicadas keep up their unrelenting chorus, hidden in the shade of the dry grass.

It's her first time in the Pyrenees, although she feels very much at home. She's been told that in the winter the jagged peaks of the Sabarthès Mountains are covered with snow. In the spring, delicate flowers of pink and mauve and white peep out from their hiding places in the great expanses of rock. In early summer, the pastures are green and speckled with yellow buttercups. But now, the sun has flattened the land into submission, turning the greens to brown. It is a beautiful place, she thinks, yet somehow an inhospitable one. It's a place of secrets, one that has seen too much and concealed too much to be at peace with itself.

In the main camp on the lower slopes, Alice can see her colleagues standing under the big canvas awning. She can just pick out Shelagh in her trademark black outfit. She's surprised they've stopped already. It's early in the day to be taking a break, but then the whole team is a bit demoralized. It's painstaking and monotonous work for the most part, the digging and scraping, the cataloguing and recording, and so far they've turned up little of significance to justify their efforts.They've come across a few fragments of early medieval pots and bowls, and a couple of late twelfth- or early thirteenth-century arrowheads, but certainly no evidence of the Paleolithic settlement which is the focus of the excavation.

Alice is tempted to go down and join her friends and colleagues and get her dressing sorted out. The cut smarts and her calves are already aching from squatting.The muscles in her shoulders are tense. But she knows that if she stops now, she'll lose her momentum.

Hopefully, her luck's about to change. Earlier, she'd noticed something glinting beneath a large boulder, propped against the side of the mountain, neat and tidy, almost as if it had been placed there by a giant hand. Although she can't make out what the object is, even how big it is, she's been digging all morning and she doesn't think it will be much longer before she can reach it.

She knows she should fetch someone. Or at least tell Shelagh, her best friend, who is the deputy on the dig. Alice is not a trained archeologist, just a volunteer spending some of her summer holiday doing something worthwhile. But it's her last full day on site and she wants to prove herself. If she goes back down to the main camp now and admits she's on to something, everybody will want to be involved, and it will no longer be her discovery.

In the days and weeks to come, Alice will look back to this moment. She will remember the quality of the light, the metallic taste of blood and dust in her mouth, and wonder at how different things might have been had she made the choice to go and not to stay. If she had played by the rules.

She drains the last drop of water from the bottle and tosses it into her rucksack. For the next hour or so, as the sun climbs higher in the sky and the temperature rises, Alice carries on working. The only sounds are the scrape of metal on rock, the whine of insects and the occasional buzz of a light aircraft in the distance. She can feel beads of sweat on her upper lip and between her breasts, but she keeps going until, finally, the gap underneath the boulder is big enough for her to slide in her hand.

Alice kneels down on the ground and leans her cheek and shoulder against the rock for support. Then, with a flutter of excitement, she pushes her fingers deep into the dark, blind earth. Straight away, she knows her instincts are right and that she's got something worth finding. It is smooth and slimy to the touch, metal not stone. Grasping it firmly and telling herself not to expect too much, slowly, slowly she eases the object out into the light. The earth seems to shudder, reluctant to give up its treasure.

The rich, cloying smell of wet soil fills her nose and throat, although she barely notices. She is already lost in the past, captivated by the piece of history she cradles in the palms of her hands. It is a heavy, round buckle, speckled black and green with age and from its long burial. Alice rubs at it with her fingers and smiles as the silver and copper detail starts to reveal itself underneath the dirt. At first glance, it looks to be medieval too, the sort of buckle used to fasten a cloak or robe. She's seen something like it before.

She knows the danger of jumping to conclusions or of being seduced by first impressions, yet she can't resist imagining its owner, long dead now, who might have walked these paths. A stranger whose story she has yet to learn. The connection is so strong and Alice is so absorbed that she doesn't notice the boulder shifting on its base. Then something, some sixth sense, makes her look up. For a split second, the world seems to hang suspended, out of space, out of time. She is mesmerized by the ancient slab of stone as it sways and tilts, and then gracefully begins to fall toward her.

At the very last moment, the light fractures. The spell is broken. Alice throws herself out of the way, half tumbling, half slithering sideways, just in time to avoid being crushed. The boulder hits the ground with a dull thud, sending up a cloud of pale brown dust, then rolls over and over, as if in slow motion, until it comes to rest farther down the mountain.

Alice clutches desperately at the bushes and scrub to stop herself slipping any farther. For a moment she lies sprawled in the dirt, dizzy and disorientated. As it sinks in how very close she came to being crushed, she turns cold. Too close for comfort, she thinks. She takes a deep breath.Waits for the world to stop spinning.

Gradually, the pounding in her head dies away. The sickness in her stomach settles and everything starts to return to normal, enough for her to sit up and take stock. Her knees are grazed and streaked with blood and she's knocked her wrist where she landed awkwardly, still clutching the buckle in her hand to protect it, but basically she's escaped with no more than a few cuts and bruises.I'm not hurt. 

She gets to her feet and dusts herself down, feeling a total idiot. She can't believe she made such a basic mistake as not securing the boulder. Now Alice looks down to the main campsite below. She's amazed-and relieved- that nobody in the camp seems to have seen or heard anything. She raises her hand, is about to call out to attract someone's attention when she notices that there's a narrow opening visible in the side of the mountain where the boulder had been standing. Like a doorway cut into the rock.

It's said these mountains are riddled with hidden passages and caves, so she's not surprised. And yet, Alice thinks, somehow, she knew the doorway was there, although there's no way of telling from the outside. Guessed, more like. 

She hesitates. Alice knows she should get somebody to come with her. It is stupid, possibly even dangerous, to go in on her own without any sort of backup. She knows all the things that can go wrong. But she shouldn't have been up here working on her own anyway. Shelagh doesn't know.And besides, something is drawing her in. It feels personal. It's her discovery.

Alice tells herself there's no sense disturbing them all, getting their hopes up, for no reason. If there is anything worth investigating, she'll tell someone then. She won't do anything. She just wants to look. I'll only be a minute. 

She climbs back up. There is a deep depression in the ground at the mouth of the cave, where the stone had stood guard. The damp earth is alive with the frantic writhing of worms and beetles exposed suddenly to the light and heat after so long. Her cap lies on the ground where it fell. Her trowel is there too, just where she left it.

Alice peers into the darkness. The opening is no more than five feet high and about three feet wide and the edges are irregular and rough. It seems to be natural rather than man-made, although when she runs her fingers up and down the rock, she finds curiously smooth patches where the boulder rested.

Slowly, her eyes become accustomed to the gloom. Velvet black gives way to charcoal gray and she sees that she is looking into a long, narrow tunnel. She feels the short hairs rise on the back of her neck, as if to warn her that there is something lurking in the darkness that would be better left undisturbed. But that's just a childish superstition and she brushes the feeling away. Alice doesn't believe in ghosts or premonitions.

Squeezing the buckle tightly in her hand, like a talisman, she takes a deep breath and steps forward into the passageway. Straight away, the smell of long-hidden, subterranean air envelops her, filling her mouth and throat and lungs. It's cool and damp, not the dry, poisonous gases of a sealed cave she's been warned about, so she guesses there must be some source of fresh air. But, just in case, she rummages in the pockets of her cut-offs until she finds her lighter. She flicks it open and holds it up to the dark, double-checking that there is oxygen. The flame gutters in a breath of wind, but it does not go out.

Feeling nervous and slightly guilty, Alice wraps the buckle in a handkerchief and pushes it into her pocket, then cautiously steps forward. The light from the flame is weak, but it illuminates the path immediately in front of her, throwing shadows on the jagged gray walls.

As she moves farther in, she feels the chill air curl around her bare legs and arms like a cat. She is walking downhill. She can feel the ground sloping away beneath her feet, uneven and gritty. The scrunch of the stones and gravel is loud in the confined, hushed space. She is aware of the daylight getting fainter and fainter at her back, the farther and deeper she goes.

Abruptly, she does not want to go on. She does not want to be here at all. Yet there is something inevitable about it, something that is drawing her deeper into the belly of the mountain.

After another ten meters the tunnel comes to an end. Alice finds herself standing at the threshold of a cavernous enclosed chamber. She is standing on a natural stone platform. A couple of shallow, wide steps directly in front of her lead to the main area where the ground has been leveled flat and smooth. The cavern is about ten meters long and perhaps five meters wide, clearly fashioned by the hands of men rather than by nature alone. The roof is low and vaulted, like the ceiling of a crypt.

Alice stares, holding the flickering single flame higher and bothered by a curious prickling familiarity that she cannot account for. She is about to descend the steps when she notices there are letters inscribed in the stone at the top. She bends down and tries to read what is written. Only the first three words and the last letter-N or H maybe-are legible. The others have been eroded or chipped away. Alice rubs at the dirt with her fingers and says the letters out loud. The echo of her voice sounds somehow hostile and threatening in the silence.

"P-A-S A P-A-S . . . Pas a pas."

Step by step? Step by step what? A faint memory ripples across the surface of her unconscious mind, like a song long forgotten. Then it is gone.

"Pas a pas," she whispers this time, but it means nothing. A prayer? A warning? Without knowing what follows, it makes no sense.

Nervous now, she straightens up and descends the steps, one by one. Curiosity fights with premonition and she feels the goosebumps on her slim bare arms, from unease or the chill of the cave, she cannot say. Alice holds the flame high to light her way, careful not to slip or dislodge anything.At the lower level, she pauses. She takes a deep breath and then takes a step into the ebony darkness. She can just make out the back wall of the chamber.

It's hard to be sure at this distance that it isn't just a trick of the light or a shadow cast by the flame, but it looks as if there is a large circular pattern of lines and semicircles painted or carved into the rock. On the floor in front of it there is a stone table, about four feet high, like an altar.

Fixing her eyes on the symbol on the wall to keep her bearings, Alice edges forward.Now she can see the pattern more clearly. It looks like some sort of labyrinth, although memory tells her that there is something not quite right about it. It's not a true labyrinth. The lines do not lead to the center, as they should. The pattern is wrong. Alice can't account for why she's so sure about this, only that she is right.

Keeping her eyes trained on the labyrinth, she moves closer, closer. Her foot knocks something hard on the ground. There is a faint, hollow thump and the sound of something rolling, as if an object has shifted out of position. Alice looks down.

Her legs start to tremble. The pale flame in her hand flickers. Shock steals her breath. She is standing at the edge of a shallow grave, a slight depression in the ground, no more than that. In it there are two skeletons, once human, the bones picked clean by time. The blind sockets of one skull stare up at her. The other skull, kicked out of place by her foot, is lying on its side as if turning its gaze away from her.

The bodies have been laid out, side by side, to face the altar, like carvings on a tomb. They are symmetrical and perfectly in line, but there is nothing restful about the grave.No sense of peace. The cheekbones of one skull are crushed, crumpled inwards like a mask of papier mâché. Several of the ribs of the other skeleton are snapped and jut out awkwardly, like the brittle branches of a dead tree.

They cannot harm you. Determined not to give in to the fear, Alice forces herself to crouch down, taking care not to disturb anything else. She runs her eyes over the grave. There is a dagger lying between the bodies, the blade dulled with age, and a few fragments of cloth. Next to it, there is a drawstring leather bag, big enough to hold a small box or a book. Alice frowns. She's sure she's seen something like it before, but the memory refuses to come.

The round, white object wedged between the clawlike fingers of the smaller skeleton is so small that Alice nearly misses it.Without stopping to think if it's the right thing to do, quickly she takes her tweezers out of her pocket. She stretches down and carefully eases it out, then holds it up to the flame, softly blowing the dust away to see better.

It's a small stone ring, plain and unremarkable, with a round, smooth face. It, too, is oddly familiar. Alice looks more closely. There's a pattern scratched on the inside. At first, she thinks it's a seal of some kind. Then, with a jolt, she realizes. She raises her eyes to the markings on the back wall of the chamber, then back to the ring.

The patterns are identical.

Alice is not religious. She does not believe in heaven or hell, in God or the Devil, nor in the creatures that are believed to haunt these mountains. But, for the first time in her life, she is overwhelmed by a sense of being in the presence of something supernatural, something inexplicable, something bigger than her experience or comprehension. She can feel malevolence crawling over her skin, her scalp, the soles of her feet.

Her courage falters. The cave is suddenly cold. Fear catches in her throat, freezing the breath in her lungs. Alice scrambles to her feet. She should not be here in this ancient place. Now, she's desperate to get out of the chamber, away from the evidence of violence and the smell of death, back to the safe, bright sunlight.

But she's too late.

Above her or behind her, she cannot tell where, there are footsteps. The sound bounces around the confined space, ricochets off the rock and stone. Someone is coming.

Alice spins around in alarm, dropping the lighter. The cave is plunged into darkness. She tries to run, but she is disorientated in the dark and cannot find the way out. She stumbles. Her legs go from under her. She falls. The ring is sent flying back into the pile of bones, where it belongs.

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Excerpted from LABYRINTH © Copyright 2012 by Kate Mosse. Reprinted with permission by Putnam Adult, an imprint of Penguin Group (USA). All rights reserved.