A boy's screams pierce the silence of the night and the village explodes into life. Warriors are already racing towards him by the time I whirl from my watching point near the gate. Torches are flung into the darkness. I see Ninian, a year younger than me, new to the watch... a two-headed demon, pieced together from the bones and flesh of the dead... blood.

Goll is first on the scene. An old-style warrior, he fights naked, with only a small leather shield, a short sword and axe. He hacks at the demon with his axe and buries it deep in one of the monster's heads. The demon screeches but doesn't release Ninian. It lashes out at Goll with a fleshless arm and knocks him back, then buries the teeth of its uninjured head in Ninian's throat. The screams stop with a sickening choking sound.

Conn and three other warriors swarm past Goll and attack the demon. It swings Ninian at them like a club and scythes two of them down. Conn and another keep their feet. Conn jabs one of the monster's eyes with his spear. The demon squeals like a banshee. The other warrior-Ena-slides in close, grabs the beast's head and twists, snapping its neck.

If you break a human's neck, that person will almost surely die. But demons are made of sturdier stuff. Broken necks just annoy most of them.

With one hand the demon grabs the head which Goll shattered with his axe. Rips it off and batters Ena with it. She doesn't let go. Snaps the neck again, in the opposite direction. It comes loose and she drops it. She pulls a knife from a scabbard strapped to her back and drives it into the rotting bones of the skull. Making a hole, she wrenches the sides apart with her hands, digs in and pulls out a fistful of brains. Grabs a torch and sets fire to the grey goo.

The demon howls and grabs blindly for the burning brains. Conn snatches the other head from its hand. He throws it to the ground and mashes it to a pulp with his axe. The demon shudders, then slumps.

"More!" comes a call from near the gate. It's late-later than demons usually attack. Most of the warriors on the main watch have retired for the night, replaced by children like me. Our eyes and ears are normally sharp. But this close to dawn, most of us are sleepy and sluggish. We've been caught off guard. The demons have snuck up. They have the advantage.

Bodies spill out of huts. Hands grab spears, swords, axes, knives. Men and women race to the rampart. Most are naked, even those who normally fight in clothes-no time to get dressed.

Demons pound on the gate and scale the banks of earth outside, tearing at the sharpened wooden poles of the fence, clambering over. The two-headed monster might have been a diversion, sent to distract us. Or else it just had a terrible sense of direction, as many corpse-demons do.

Warriors mount ladders or haul themselves up on to the rampart to tackle the demons. It's hard to tell how many monsters there are. Definitely five or six. And at least two are real demons- Fomorii.

Conn arrives at the gate, shouting orders. He bellows at those on watch who've strayed from their posts. "Stay where you are! Call if clear!"

The trembling children return to their positions and peer into the darkness, waving torches over their heads. In turn they yell, "Clear!" "Clear!" "Clear!" One starts to shout "Cle-", then screams, "No! Three of them over here!"

"With me!" Goll roars at Ena and the others who fought the first demon. They held back from the battle at the gate, in case of a second attack like this. Goll leads them against the trio of demons.

I see fury in his face-he's not furious with the demons, but with himself. He made a mistake with the first one and let it knock him down. That won't happen again.

As the warriors engage the demons, I move to the centre of the rath and wait. I don't normally get involved in fights. I'm too valuable to risk. If the demons break through the barricades, or if an especially powerful Fomorii comes up against us-that's when I go into action.

To be honest, I doubt I could do much against the stronger Fomorii. Everybody in the rath knows that. But we pretend I'm a great priestess, mistress of all the magics. The lie comforts us and gives us some faint shadow of hope.

The younger children of the rath cluster around me, watching their parents fight to the death against the foul legions of the Otherworld. Their older brothers and sisters are at the foot of the rampart, passing up weapons to the adults, ready to dive into the breach if they fall. But these young ones wouldn't be of much use.

I hate standing with them. I'd rather be at the rampart. But duty comes at a price. Each of us does what we can do best. My wishes don't matter. The welfare of the rath and my people comes first. Always.

One of the Fomorii makes it over the fence. Half-human, half-boar. A long jaw. A mix of human teeth and tusks. Demonic yellow eyes. Claws instead of hands. It bellows at the warriors who go up against it, then spits blood at them. The blood hits a woman in the face. She shrieks and topples back off the rampart. Her flesh is bubbling-the demon blood is like fire.

I race to the woman. It's Scota. We share a hut sometimes (I'm passed around from hut to hut now Banba's gone). Her usually pale skin is an ugly red colour. Bubbles of flesh burst. The liquid sizzles. Scota screams.

I press my palms to her forehead, ignoring the heat of her flesh and the burning drops of liquid which strike my skin. I mutter the words of a calming spell. Scota sighs and relaxes, eyes closing. I tug a small bag from my belt, open it and pour coarse green grains into the palm of my left hand. Dropping the bag, I spit over the grains and mix them together with a finger, forming a paste. I rub the paste into Scota's disfigured flesh and it stops dissolving. She'll be scarred horribly but she'll live. There are other pastes and lotions I can use to help the wounds heal cleanly. But not now. There are demons to kill first.

I look up. The boar demon has been pierced in several places by the swords and knives of our warriors, but still it fights and spits. I wish I knew where these monsters got their unnatural strength from.

Screams behind me-the children! A spider-shaped Fomorii has crawled out of the hut over the souterrain. The beast must have found the exit hole outside the rath and made its way up the tunnel, then broke through the planks covering the entrance.

Conn hears the screams. He looks for warriors to send to their aid. Before he can roar orders, two brothers hurl themselves into the demon's path. Ronan and Lorcan, the rath's red-headed twins, barely sixteen years old. Their younger brother, Ere, was killed several months ago. The twins were always strong fighters, even as young children, but since Ere fell, they've fought like men possessed. They love killing demons.

Conn refocuses on the demons at the gate. He doesn't bother sending other warriors to deal with the spider. He trusts the teenage twins. They might be among the youngest warriors in the rath, but they're two of the fiercest.

Ronan and Lorcan move in on the spider demon. Now that it's closer, I see that although it has the body of a large spider, it has a dog's face and tail. Demons are often a mix of animals. Banba used to say they stole the forms of our animals and ourselves because they didn't have the imagination to invent bodies of their own.

Ronan, the taller of the pair, with long, curly, flowing hair, has two curved knives. Lorcan, who cuts his hair close and whose ears are pierced with a variety of rings, carries a sword and a small scythe. They're both skilled at fighting with either the left or right hand. But before they can tackle the dog-spider, it shoots hairs at them. The hairs run all the way along its eight legs and act like tiny arrows when flicked off sharply.

The hairs strike the brothers and cause them to stop and cover their faces with their hands, to protect their eyes. They hiss, partly from the pain, but mostly with frustration. The Fomorii moves forward, barking with evil delight, and the twins are forced back, chopping blindly at it.

I could call Conn for assistance, but I want to handle this on my own. I won't place myself at risk, but I can help, leaving the warriors free to concentrate on the larger, more troublesome demons.

I hurry to the beehives. We kept them outside the rath before the attacks began, but certain demons have a taste for honey, so we moved them in. The bees are at rest. I reach within a hive and grab a handful of bees, then prise them out, whispering words of magic so they don't sting me. Walking quickly, I place myself behind Ronan and Lorcan. Taking a firm stance, I thrust my hand out and whisper to the bees again, a command this time. They come to life within my grasp.

"Move!" I snap. Ronan and Lorcan glance back at me, surprised, then step aside. I open my fingers and the bees fly straight at the dog-spider, attacking its eyes, stinging it blind. The Fomorii whines and slaps at its eyes with its legs, losing interest in everything except the stinging bees. Ronan and Lorcan step up, one on either side. Four blades glint in the light of the torches-and four hairy legs go flying into darkness.

The demon collapses, half its legs gone, sight destroyed. Ronan steps on its head, takes aim, then buries a knife deep in its brain. The dog-spider stiffens, whines one last time, then dies. Ronan withdraws his knife and wipes it clean on his long hair. His natural red hair is stained an even darker shade of red from the blood of demons. Lorcan's stubble is blood-caked too. They never wash.

Ronan looks at me and grins. "Nice work." Then he runs with Lorcan to where Conn and his companions are attempting to drive the demons back from the fence.

I take stock. Goll's section is secure-the demons are retreating. The boar-shaped Fomorii has been pushed back over the fence. It's clinging to the poles, but its fellow demons aren't supporting it. When Ronan and Lorcan hit, blades turning the air hot, it screams shrilly, then launches itself backwards, defeated. Connla-Conn's son-fires a spear after the demon. He yells triumphantly-it must have been a hit. Connla picks up another spear. Aims. Then lowers it.

They're retreating. We've survived.

Before anyone has a chance to draw breath, there's a roar of rage and loss. It comes from near the back of the rath-Amargen, Ninian's father. He's cradling the dead boy in his arms. He had five children once. Ninian was the last. The others-and his wife-were all killed by demons.

Conn hurries across the rampart towards Amargen, to offer what words of comfort he can. Before Conn reaches him, Amargen leaps to his feet, eyes mad, and races for the chariot which our prize warriors used when going to fight. It's been sitting idle for over a year, since the demon attacks began. Conn sees what Amargen intends and leaps from the rampart, roaring, "No!"

Amargen stops, draws his sword and points it at Conn. "I'll kill anyone who tries to stop me."

No bluff in the threat. Conn knows he'll have to fight the crazed warrior to stop him. He sizes up the situation, then decides it's better to let Amargen go. He shakes his head and turns away. Waves to those near the gate to open it.

Amargen quickly hooks the chariot-a cart really, nothing like the grand, golden chariots favoured by champions in the legends-up to a horse. It's the last of our horses, a bony, exhausted excuse for an animal. He lashes the horse's hind quarters with the blunt face of his blade and it takes off at a startled gallop. Racing through the open gate, Amargen chases the demons and roars a challenge. I hear their excited snorts as they stop and turn to face him.

The gate closes. A few of the people on the rampart watch silently, sadly, as Amargen fights the demons in the open. Most turn their faces away. Moments later-human screams. A man's. Terrible, but nothing new. I say a silent prayer for Amargen, then turn my attention to the wounded, hurrying to the rampart to see who needs my help. The fighting's over. Time for healing. Time for magic. Time for Bec.