Chaos. Everyone's running, crashing into each other, falling, screaming. I'm part of the madness. Clutching Art in my arms. Fleeing blindly. Away from the grey light and the four-armed monster. Trying to stay on my feet. Weeping, partly because Logan has been killed, mostly because I'm terrified.

A girl smashes into me and knocks me to the ground. I manage to fall with Art on top of me, so he isn't injured. He's laughing - he thinks this is a game. I start to yell at the girl, but then I see blood gushing from her throat, her arms thrashing. She topples over. Flops about, then goes very still.

I look away before I can focus on her face. I don't want to know who she is. Right now I want to concentrate on the one thing that matters more than anything else - getting out of here before the monster kills me.

I push myself to my feet, chest heaving. Look for the best way out. It's hard to tell. I'm surrounded on all sides by panic. I count two, three, four dead children - then stop. I don't want to know the numbers.

The monster's on top of a boy - Dave English, who was so afraid of death. The beast's fingers are buried in Dave's stomach. It's gazing around, white eyes darting from one child to another. Like it's choosing its next victim. Or looking for someone in particular.

I'm getting ready to run again when I spot movement in the panel of grey light. A man steps through. Behind him is a blonde woman. Another woman after her, Indian, wearing a sari. Then a second dark-skinned man.

The Indian woman curses when she sees the corpses. Starts after the monster, her hands coming up, murder in her eyes.

"Sharmila! No!" barks the first man. He's old. He has a short beard and messy dark hair. A shabby suit.

"We must stop this!" the Indian woman shouts.

"No," the man repeats, and I can tell by his tone that he's accustomed to being obeyed.

"Master..." the second man says uncertainly. He has the darkest skin I've ever seen, as if his mother was the night.

"I know, Raz," the first man snaps. "But we mustn't kill him."

"The children," the Indian woman snarls. "I will not stand by and let that demon murder all these children. That would be monstrous."

"She is right, master," the black man says.

"Oh, very well," the man in the shabby suit grumbles. "We'll save as many of the young as we can. We don't want to be considered barbarians." He laughs then signals for the others to spread out. "Work Cadaver back to the window and force him through. We'll track him down again later."

This sudden appearance and surreal conversation has astonished me so much, I'm standing still instead of fleeing for safety. The monster - a demon, the woman said - has moved on from Dave English and is lolloping after a girl. She's racing from it like an Olympic sprinter, but the monster's legs are longer and it catches up with her in a couple of seconds. Reaches out with its long, hairy fingers... then recoils when the ground at its feet explodes upwards.

The demon makes a high whistling sound, its head snapping round. It spots the four humans who came through the panel (or window, as the man called it). It glares at them, white eyes filled with fury and hate. They're closing in on it from both sides, leaving a path to the window free. Pale blue light crackles from the black man's fingertips - I guess he made the ground explode, distracting the monster and saving the girl.

Art bites my right arm, hard. It's the first time he's ever bitten me. I get such a shock, I drop him and collapse on my bum. He lands with a heavy thud, rolls over, then crawls towards the demon, gurgling happily. He must think it's some giant toy. He's so anxious to play with it, he bit me so I'd release him.

"Art!" I yell. "Come back! It's..."

The demon spots me. Its white eyes roll down and fix on Art. It gives a loud, high-pitched whistle. And then it's running towards us, impossibly long steps. I barely have time to register fear - then it's on us. It stoops, picks Art up with one hand, hisses like a nest of snakes.

"No!" I cry, leaping at the demon, forgetting my fear, caring only about Art. I land on the monster's left side. From a distance I thought its skin was leathery, but now I realise it's more like an insect's brittle shell. My fists crunch into it, knocking crinkly flakes loose. I'm yelling wildly, the way I always do when I get into a fight.

I tug at its hairy arms - they feel like strands of seaweed - desperately reaching for Art. The demon hisses again then knocks me aside. I land hard on my right arm. It twists beneath me and snaps. I roar with pain, but roll over and force myself back to my feet, woozy but determined to rescue Art.

But the demon isn't there. It's racing towards the grey window, Art cradled in its arms, head down, legs a whirl of motion.

"Beranabus!" the Indian woman shouts.

"Let him go," the leader of the quartet says.

"But the child..."

"Not our problem."

"Art!" I bellow, tears streaming from my eyes. It's hopeless, but I run after the demon, praying for the strength and speed to draw level with it before it reaches the window.

The demon pauses at the panel of grey light. Looks back at the four adults. It hisses and shakes Art at them, mocking them. The hairs of its hands wrap round Art's ankles then snake up his legs. He's giggling, tugging at the monster's floppy ears, no idea of the danger he's in. He drops his orange marbles - he's found something better to play with.

The Indian woman snarls and extends a hand towards the demon. She starts muttering the words of what sounds like a spell. Before she can complete it, the monster jumps at the window, hits the grey light and vanishes. Returns to whatever hellish place it came from - with Art.

I sink to my knees, stunned, staring at the window. Around me - screams, sobbing, moans. The stench of blood and death. Calls from the village as terrified adults race towards their stricken children, too late to help, only in time to mop up the blood.

The four people who came through after the monster have gathered by the window. The light is pulsing again. The edges are throbbing inwards, turning white. The leader stands in front of the panel.

"Do you think he's waiting for us on the other side?" the dark-skinned man asks.

The leader shrugs. "Only one way to find out." He steps forward and disappears like the demon. The blonde woman follows, then the black man. The Indian woman pauses and looks round the field of misery. Her gaze rests on me. She winces. Starts to say something. Changes her mind and steps into the light.

I'm dazed. Shaking from shock and the pain in my right arm. Silently staring at the grey light as it pulses quicker and quicker, the edges closing in. It's about to collapse, break apart, become fragmented patches of light again.

Fresh screams as parents find the remains of their children. A chorus of wails, growing by the second, becoming a wall of anguished sound. Some kids are still running. They don't know it's finished, that the monster's gone, that the last victim was Art.

I stumble towards the flickering window, wanting to believe there's hope, that the Indian woman will reappear with Art in her arms. Art can't be gone forever. I can't have lost him. He's my brother.

I spot the marbles on the ground by the window. I pick them up, study their orange centres, then put them in my left trouser pocket. I'm numb. Hardly aware of the throbbing pain in my broken arm.

I think about Mum and Dad, how they'll react when they return to find Paskinston in mourning, Art abducted. Mum's last words to me echo inside my skull - "Look after your brother." Dad calling me the best brother in the world, saying I'd take better care of Art than they could.

But I didn't. I let a demon take him.

Staring into the heart of the grey light. I tune out the screams. Focus on the window. A voice whispers to me, a voice I haven't heard for a year. Tells me what I must do. What it suggests is crazy. I should dismiss it immediately. But I can't.

The window is closing. Any second now, it'll be gone. But if I step forward before it closes... chase after the demon... perhaps I can find Art, rescue him, bring him back home.

Madness. Art's probably dead already, slaughtered by the demon as soon as it escaped. Besides, I don't know what lies on the other side of the window. Most likely more monsters like the one that took Art. I'll almost certainly be killed. Even if I'm not, there'll be no way back once the window breaks up. Mum and Dad will lose both their children. Double the sorrow. I should forget about it. Ignore the voice and its suicidal suggestion.

But I can't. Because they'll blame me. They won't want to, but the accusation will be there, in their eyes. A look that says, "You didn't take care of him. He was your brother. You didn't protect him. You let him go. It's your fault."

The edges of the window bend inward. The grey light sputters. There's no more time. I have to decide.

I start to look back, wanting the window to close before I can act, to cheat myself of the chance to go after Art. But as my head turns, my feet move forward. Instinct makes me step through the grey light of the window - into the realm of the murderous demon.