The tunnel. The rent between this world and the Demonata's. The passageway for demons. The source of the nightmares.

We're here.

It's an hour or so before sunset. We've set the horses free and are on our knees, hiding behind bushes, studying the scene. A hole in the ground ahead is the focal point. The branches of the trees around it are thick with strips of cloth, bits of wood, bodies of the dead. A solid ceiling, like the one around the ring of magical stones where we sheltered earlier, in what feels now like a separate age.

Beneath the cover of the trees-hordes of demons. Most sleeping. Some fighting, playing with dead bodies, eating. Every disgusting shape and shade imaginable. Some undead too, but not many.

"We'll never get through them all," Goll whispers.

"I could create a diversion," Lorcan suggests. "Attack at one side and draw them away. The rest of you could sneak in while they were dealing with me."

"No," Goll says. "That wouldn't work. Maybe Bran could dance and lead them astray."

"Run fast," Bran says, nodding vigorously.

"Too many," Drust mutters. "Not all would be lured away."

"Magic?" I ask. "A masking spell?"

Drust nods. "That's our best hope but we can't count on it. These are superior to most of the demons we've faced. They're some of the more powerful demons who have crossed, placed here by their masters to guard the opening."

"Then they might see through the spell," I note.

"Aye. But we'll have to risk it. We'll cast a strong spell over you, me and Bran, then advance. Goll, Lorcan and Connla can attack at the same time, at different spots, to create distractions."

"Sounds good to me," Goll says. "How about you, my fine young...?" He stops, brow furrowing as he stares at Connla. The vain warrior has cut the flesh of both his palms and is daubing his cheeks and forehead with blood, quietly muttering words which could be either a spell or a prayer. "What are you doing?" Goll asks suspiciously.

Connla finishes the spell or prayer, then smiles. "A bit of added protection."

"That won't help," Drust says.

"We'll see," Connla chuckles, casually glancing over the top of the bush at the demons. "Well, I'm ready. Make up your minds, tell me what you want to do and on we'll go."

Drust regards Connla with uneasy surprise. Some warriors are never afraid going into battle, but Connla isn't one of them. Yet here he squats, more at peace than anyone, looking like a man with nothing to lose or no notion of losing.

"You understand what we're discussing?" Drust asks. "If you fight, you'll die. It will take time to cast the spells of closure. The demons will kill you while we're at work."

"Just worry about your magic, druid," Connla laughs. "Leave us to handle the fighting."

"A man at last," Goll remarks wryly, then faces Drust. "So the three of us will attack the demons while you, Bran and Bec forge ahead on your own?"

Drust hesitates, then abruptly changes his mind. "No. Some demons may have orders to stay by the entrance in case of an attack. It might be better if we don't give them advance warning. We'll stick together and push on as a group. If they see through the spell, Bec and I will make a dash for the hole and the rest of you can fight then."

"We won't let you down," Connla says grandly.

Drust and I concentrate and draw upon our magic. The night's rest has done me a world of good, even though I didn't sleep. I feel power bubbling up inside, stronger than ever. When I cast the masking spell, I add a few twists to it, improvising, improving on the spell which Drust taught me. The druid feels the strength of the new spell. He's surprised, but follows my lead, and we carefully wrap our small group safely within it.

"The spell will trail us," I tell Drust when we're finished. "We won't need to maintain it as we walk. We can focus on the task ahead."

"How did you manage that?" he asks, slightly jealous.

I shrug. "It just came to me."

Drust sighs. "Such promise. There's so much you could do, maybe more than any magician has ever done. I wish..." He stops and steels himself. Checks that everybody has a weapon to hand (except simple Bran). Then we push through the bush and enter the camp of the Demonata.

The spell holds. We edge through the demonic ranks, carefully stepping over tentacles and twisted limbs, ignoring the stench of rotting human bodies and the even fouler smells of the demons. Most are larger than any who attacked our rath. They look fiercer and stronger. I don't think we would have survived an assault by this lot. Yet these aren't the strongest Demonata, only the more worthy servants of the demon masters.

Until this moment I didn't truly believe the demons would overrun the land. I was inwardly sure that my people would fight hard and win in some places, repel the demons, hold their own. Now I know I was wrong. If we fail and the demon masters cross, all will fall in quick succession. Depending on how fast the demons move, this entire land could be a steaming pile of ruins, broken bones and decaying flesh within a week.

Bran studies the demons with interest, smiling at some of the more hideously deformed monsters. Connla casts a cool eye over them, acting unimpressed, as if they were a flock of scraggly sheep. Everybody else looks at them with disgust and fear.

A four-headed, red-skinned demon stirs and looks right at me. I freeze, certain it's seen through the spell. But then it belches, spits out a chewed-up hand and lowers its head again. I step over the half-dissolved, bile-speckled hand and fight to keep my stomach quiet as we pass the dozing monster.

Close to the hole. It looks like a natural rip in the earth, though the area around it has been torn at and dug up, to enlarge the mouth. No demons rest close by-they keep at least six or seven paces away from the hole.

We slip through a space between two misshapen demons and enter the clearing. Drust walks to the rim of the hole and looks down. I step up beside him and see a long shaft angling down, deep into the earth. Unnatural heat billows from it. I want Drust to start the spells here, close the tunnel from this point, not lead us down that shaft to whatever horrors lie beneath.

But Drust points down, as I knew he would. He makes sure we all understand, then lowers himself into the hole, searching for handholds, descending into the darkness of the pit. I go next, then Bran, Lorcan, Goll. Connla brings up the rear.

The rock is hot to the touch but bearable. Lots of holds. Easy to climb. The shaft turns to the left after a while. Pure darkness around the bend. I pause, look up at the overcast but beautiful, human evening sky one last time, then slide across into eternal, demonic night.

We climb for five minutes, ten, slowly feeling our way down. I could cast a lighting spell but Drust hasn't, so I don't think I should either. I'm expecting the descent to last for ages. But a few minutes later we hit level ground and are soon standing in a huddle, not sure what to do next, afraid to continue in case we're on a platform overhanging a deadly drop.

"I'm going to feel ahead with magic," Drust whispers. "You try too. Explore with your mind. Try and determine where we are and what lies ahead."

I close my eyes-not that it makes any difference in this place-and send out mental feelers. But I'm not very good at this type of magic. I get the sense of a large space around us-a cave, I think- but I can't be sure of its exact size. And I've no idea what the ground is like underfoot, whether it's solid, breaks off into nothingness after a few feet, or is littered with traps.

Fortunately Drust is more accomplished at this than me and a minute later he sighs the contented sigh of a man who has finally found what he's been looking long and hard for. "It's all right," he says, excitement in his voice. "We're here."

Light flares dimly in his left hand. Slowly, he lets it grow and expand, filling his palm and then rising to hang in the hot air above us. It lights up the entire cave, revealing a site of beautiful wonders and a wretched terror.

The wonders-V-shaped, glistening formations of a substance not quite rock. Some reach up from the floor, others hang from the ceiling. All sorts of sizes. Water drips from the tips of some of the overhanging shapes, to splash over the floor of the cave or one of the uprising Vs. In some places it's as if the shapes are reaching for each other, growing towards one another.

There are other formations stretched between the floor and ceiling, some huge, others tiny bulges. And an underground waterfall to our right, the water appearing as if by magic from high up the wall, vanishing through a crack in the rocks underneath, flowing on to who knows where.

This is what I imagine the Otherworld or Tir na n'Og to be like. It doesn't feel as if it belongs to our world. It's so quiet-except for the noise of the waterfall-and peaceful. I feel like if I fell asleep, I could snooze for a hundred years and not be any different when I awoke. Time doesn't touch this cave-or if it does, it touches it softly, slowly, subtly.

But then there's the wretched terror, which is almost impossible to comprehend. And difficult to describe.

There's a hole-the start of the tunnel-in one of the walls of the cave. And around and within it, the head and warped body of a man. The head hangs just above the hole, limp, its neck jutting out of the rock. Its body is spread out around it, mixed in with the rock, part of the wall. An arm far off to the left. A leg farther down to the right. The chest and stomach torn open, surrounding the hole, some inner organs visible inside the mouth of the tunnel.

At first, I think it's a trick of the rock formation, that the head has been stuck there to emphasise the strange nature of the hole. Then I think that the body just adorns the outside of the rock, that bits and pieces have been stuck on or crammed into cracks. But as we move closer, drawn to it in silent fascination and horror, I see that isn't right either.

The body is the rock. Somehow the two exist together, occupying the same space. It's as if the rock melted and the man stepped into it, coming apart as the rock grew hard again around him. It must have been a painful way to die. Was he sacrificed? Did demons melt the rock and then-

The head bobs up and its eyes flicker open. I stifle a scream. There are gasps all around me. Goll, Lorcan and Connla raise their weapons automatically.

"No," Drust says, signalling for calm. "It's all right. He can't harm us."

"Don't be... so... sure," the man in the rock croaks.

"Balor's eye!" Goll exclaims. "It speaks!"

"What is it?" Lorcan asks. "What manner of...?" He stops, eyes narrowing. Takes a step ahead of everyone, gazes at the face for a long moment, then looks back at Drust. "Druid, what spell is this? That face is yours!"

I don't understand what he's saying until I look again and see that the face hanging from the rock is very similar to Drust's. Stubbly hair. Agonised eyes. A fuller beard. But his shape, his mouth, his expression.

"His name was Brude," Drust says quietly, eyes locked with the man's. "My twin brother. A druid like me."

"Brotherrrrrr," the man who once was-or still is-Brude sighs, then chuckles creakily. "You have... come... to witness... the glory?"

"Brude hated Christians more than most," Drust says, ignoring the question. "I was never sure why."

"Because... they... corrupt," Brude hisses, eyes filling with fury. "They... change... that which... should not... be changed. They... destroy."

"He decided to fight them," Drust continues. "He sought a way to defeat them. Magic failed him. So did brute force when he tried to organise an army to lead against them. In the end he resorted to..." He trails off into silence for a moment, then speaks again, louder this time. "He opened the tunnel between our world and the Demonata's. Invited the demons to cross. He's responsible for all the savagery and deaths. He's the one we must stop if we are to close the-"

"That's why you came!" I cry suddenly. "The other druids refused to help, but your twin was the cause of the invasion. You felt guilty. You couldn't bear to let so many people die because of him."

Drust nods slowly. "We were like two parts of the same person when we were children. If he cut himself, I hurt. When I was happy, he laughed. That changed with time, but the bond was always there, linking us, binding us. What he's doing is wrong. Christianity can't be fought-and even if it can, it should be fought by human means, not demonic. I couldn't stand by and let my brother-my own flesh and blood-commit such an atrocity against the entire human race. I had to stop him."

"Not such a noble cause then," Connla snickers. "You didn't rush to our rescue because you cared for us, but because you didn't like what your twin was up to."

Drust shrugs. "Do my motives matter? I came. I wish to put a stop to the madness. That should be enough."

"Can't... stop," Brude growls. Now that I'm closer I can see his heart, beating slowly within the wall, the rock pulsing along with it. So he's not just alive within the rock-the rock is alive too.

"It has to stop," Drust says. "This is wrong, Brude. The Demonata will destroy everything. They won't stay on this island-they'll find a way to cross the sea and spread throughout the world, killing all in their path."

"Good," Brude gurgles. "I want... them to. Except... our kind. The druids will... stand firm. We won't... fall. The weak... will perish. The strong... will remain. The way it... should be."

Drust shakes his head. "Even the druids would fall in the end. The Demonata don't share, or even rule. They consume. All would fall to them-human, priestess, druid. All."

Brude sneers. "If so... so be it. Better a world... of demons... than one... of Christian stain."

"This is pointless," Goll grunts. "We could stand here arguing forever and not get anywhere. Will I chop his head off at the neck and have done with it?"

"That won't stop him," Drust says, moving closer, breaking eye contact with his brother to motion me forward. "Brude's spirit is infused with the rock. He has become part of the tunnel between worlds. He is beyond physical harm. We can only kill him by closing the tunnel."

"Then do it, quick, and let's be out of here," Lorcan says, eyeing Brude uneasily, tugging nervously at his earrings, one after the other.

"You are a... twin too," Brude says bitterly. "I can... tell. What would you... think if... your brother... spoke of killing... you?"

"If I was in your place, I'd say he had every right to spill my blood," Lorcan answers stiffly.

"You lie," Brude snarls. "Twin should... never raise a hand... against twin." His snarl turns to a smile. "But... in this case... I don't think... it will come to... that. I smell... a friend... among my... foes. He will... protect me."

Goll frowns. "What's he talking about?"

"Ignore him," Drust mutters. "He's mad. Let's push on and-"

A cry of pain stops him. It's Lorcan. As I whirl, the teenage warrior falls to the ground, clutching his chest, blood pouring out around his fingers.

"Demons!" Goll shouts, turning sharply, sword raised. He stops, bewildered. There are no demons in the cave behind Lorcan. Only Connla-with a blood-red knife and a killer's smile.

Before anyone can react, Connla races to the cave entrance and roars up the shaft, "Demonata! Hurry to my side! There are enemies in your midst!"

Goll curses vilely and starts across the cave. But then we hear the sounds of demons pouring into the hole above and scrambling down the shaft. Goll stops, not sure what to do.

Drust ignores the chaos above us. He steps up, so he's almost face to face with his twin, then speaks to me from the side of his mouth. "I'm going to start the spells. When I complete the first one, we'll be able to enter the tunnel, where I'll finish the rest."

"What about-" I begin.

"No time!" he shouts. "Ask them to fight and buy a few seconds for us, and pray that's enough."

His lips start moving at an unnatural speed and his hands come up, glowing a dark blue hue. Brude curses him but Drust ignores the foul insults and carries on with the spell.

I turn my attention to Connla and Goll. Connla is standing by the side of the entrance, whistling merrily, cleaning under his fingernails with the tip of his bloodied knife. Goll has helped Lorcan back to his feet-Connla must have missed the young warrior's heart because although he's wounded fatally, he isn't dead. Bran stares at the blood on Lorcan's chest, head cocked sideways, not sure what to make of it.

From the shaft come screams of outrage. The demons must have piled down too fast, too many of them, and jammed. But the blockage can't last long. They'll be upon us in a minute or so, I guess.

"Why?" Goll roars at Connla. "We'll all die now!"

"You'll die," Connla replies smugly. "Not me. I've cut a deal with the demon master, Lord Loss."

"The night when he was talking to you!" I gasp, remembering our first encounter with Lord Loss, finding him crouched over Connla, whispering.

"Aye," Connla smiles. "I wasn't asleep. He came to me. Told me everything, of Drust's quest, his real reason for coming, what would happen if-when-he failed. For my cooperation he promised great power. In the new world I will be a high king, in command of all those whom the demons choose to spare."

"Weren't you listening?" I cry. "They won't spare anyone!"

"Of course they will," Connla laughs. "Every master needs slaves."

"Did Lord Loss actually say that?" I ask.

"Not directly, no, but it was implied."

"You're an ass!" Goll spits. Then he squints at Connla. "What do you mean by cooperation! What did you do for the demon?"

"Information," Connla murmurs. "I told him about you all, your pasts, your strengths and weaknesses. I told him about Orna's children-that's how he knew to fetch them. And then there were the services rendered..."

From the sounds in the shaft, the jam has cleared and the demons are moving forward again. Time's almost up. I glance desperately at Drust but his lips are still moving and he hasn't stepped forward.

"Be quick!" Goll shouts at Connla. "They'll be on us in seconds and I don't want to die without knowing the full extent of your treachery."

"Very well." Connla grins at Lorcan. "I killed Ronan-I pushed him off the cliff." Lorcan tries to curse but his face twists with pain and he only doubles over and grunts. "And Fiachna," Connla continues, laughing at me now. "Lord Loss gave me a pouch of poisoned powder. I rubbed it into Fiachna's wound after he'd been bitten by the demon, when everyone was asleep or preoccupied. I-"

Whatever he was about to say is lost as the first demon crashes through the entrance into the cave. It falls on its face but is up in an instant, head swivelling, searching for the source of danger. It spots Connla, takes a step towards him, then sniffs the air, pauses and turns its gaze on the rest of us, leaving the smirking traitor alone.

The demon bounds forward, shrieking. Goll meets it solidly, drives his sword through the tip of its head, then kicks it into the path of those which are following.

Lorcan shrugs off his death and lays into the demons with his sword, pushing forward, keeping one hand over the hole in his chest to stem the flow of blood.

Bran dances around the cave, over, under and around the demons spilling into it, confusing and enraging them, doing what he can to draw their attention away from the rest of us-and especially from Drust, still muttering his spell in front of the abusive Brude.

I reach within, call upon my magic and unleash it. I set a demon on fire. Make another's eyes pop. I drive one mad by squeezing its brain-in its madness it attacks those around it.

The spells come quickly to my tongue, power flowing through me, building up and dispersing through my fingers, lips and eyes at a frightening speed. I make one demon's stomach explode. I cause a host of the V-shaped formations overhead to snap free and fall, killing several demons in the process.

But it isn't enough. More come. An endless flow. Streaming into the cave. Lorcan has disappeared under an avalanche of monsters. I see one of his ring-pierced ears fly high into the air- my final glimpse of him. Goll's stomach has been ripped open and half his face clawed away. He fights on but it's hopeless. I can't save the old warrior. Bran is still going strong, fast and agile as ever, but what good is that?

I catch sight of Connla, moving among the demons like a master through a pack of hounds. Many growl at him suspiciously but when they smell his blood they leave him be. He's laughing at the carnage. Angling for Drust, twirling a knife, preparing to kill the druid. I start a spell to make his brain melt in his head-but then I have a better idea.

A moving spell. I cast it quickly and Connla flies across the cave, colliding with the wall beneath the waterfall. He falls heavily, then sits up, wincing but otherwise unharmed, shaking his head as water cascades over him.

"You'll have to do better than that!" he chortles, wiping water from his eyes.

"I don't think so," I retort.

He frowns at my tone. A demon standing close to him, with a head that's mostly human except for an extra eye in the middle of its forehead, sniffs at Connla uncertainly, then hisses with delight. Its mouth opens wider than any human's-row upon row of dagger-like teeth and two forked tongues.

Connla stares at the demon, confused. Then he realises-the water has washed the blood from his face! A moment of panic. He tries to cut his palms again, to redaub his cheeks. But the demon's upon him before he can restore his protective spell. It bites at his face. Catches his lips. It looks as though the pair are kissing-until the demon rips free, tearing Connla's mouth away, leaving him to fall, gibbering madly, and be set upon by a handful of other savage demons.

"Hah!" Goll shouts, taking great pleasure from Connla's savage death. "That'll teach him! Well done, Little One!"

Then a demon knocks the old warrior's legs out from under him. He falls. Demonic bodies fill the space around him. And the one-eyed ex-king who was like a father to me-who gave me my name-is gone.

Alone. No time to mourn. The demons are closing in, ignoring the dancing Bran, focusing on me. I lash out at them with every spell at my disposal, wreaking havoc. But I can't kill them all. They're getting closer. Almost upon me. Any second now, one will lurch within striking distance and then-

A hand grabs the neck of my tunic. I'm hauled backwards. I cry out, but the cry's cut short by the V of the tunic digging into my throat. I land hard on the ground. Scrabble to my feet, trying to clear my throat, to cast a spell, to take at least one more demon down with me before...

I stop. I'm in the gut-studded tunnel. Drust is beside me. The demons are at the mouth, howling, reaching for us, lashing out with all their force and fury-but not connecting. Unable to break through the invisible barrier which separates Drust and me from them.

"A positive start," the druid says. He smiles quickly, then half-closes his eyes and moves down the tunnel, muttering the words of the next spell.

I laugh hysterically and pull faces at the furious, thrashing demons. But then I recall the deaths of my friends and my crazy humour passes. I look for the bodies of Goll and Lorcan but I can't see through the demons crowded around the mouth of the tunnel. There's no sign of Bran either, but I'm sure he's safe-daft as he is, he leads a charmed existence. I don't think any of these demons can harm him.

I sigh heavily and wipe tears from my eyes, thinking about Goll and Lorcan, all the good times and adventures we shared. Then, putting soft thoughts behind me, I make myself hard, turn my back on the demonic chaos and set off after Drust, readying myself for a swift, victorious death.