“So I could pick up a knife, but not stab someone with it.”

“You don’t have any substance, Hargreaves. You can feel yourself touch things, even knock things over. But you can’t pick anything up; people would notice stuff floating around.”

He frowned. “OK. You’re touching this bus. Shouldn’t I fall through the floor?”

“Everyone on the bus is wearing shoes, Hargreaves. No one is touching the floor directly. You won’t fall through it.”

Tentatively he reached for the back of my seat again. His hand continued through wood and plastic until he groped my shoulder.

“Get off,” I hissed and shrugged him away.

Justin stared at his hands. “You’re the only one I can touch. Ever?”

“Sorry.” I loaded my voice with sarcasm. “Look, once I’ve found your killer and transferred this Mark you left on my hand, you can move on and we’ll never have to see each other again.”

“But…” Justin looked up and his eyes swam with tears. “But I never…” his voice trailed off. His hands dropped to his lap. “I’m going travelling after A-levels. I thought I’d go back to Dubai for a bit. I’m applying to do engineering at Cambridge next year.” His voice broke. “Tammy and I…”

I saw his throat move like he was trying to swallow a huge lump. “I never did anything.”

I bit my lip. “I’m sorry,” I said and I actually was. “If you can tell me how it happened, we can… OK, we can’t make it right but I can avenge you. It’s what I do.”

Justin looked up with red-rimmed eyes. “This is bull.” He hurled himself from his seat and lunged for the back of the bus.

“Come back.” I grabbed for his jacket, but missed.

Ignoring me, he leaped off the bus and onto the Hammersmith overpass, dodged through the traffic and disappeared from view.

Stunned, I stood and wobbled with the movement of the vehicle. “Dammit.” I examined my hands, one clean, the other stained with a blemish that screamed murder. The Darkness was coming. And without Justin, I had no way of getting rid of the Mark before it came for the one carrying it.

Dad holds my hand as I squirm. His new wheelchair digs into my side, but he doesn’t loosen his grip. I’m supposed to be looking at the coffin, or maybe the priest, but there’s a man striding towards us across the graveyard.

He’s wearing a white coat: a doctor’s uniform. A stethoscope bangs against his chest as he nears. Why would a doctor be coming to the funeral? Even if I recognised him, or if he was one of Dad’s new friends, wouldn’t he have dressed in black like everyone else? The signs are there: he’s a ghost.

I try to pull free of Dad’s fingers and he leans across to put his mouth to my ear. “Stop it,” he hisses. His anger heats my face.

“But–”

“This is your mother’s funeral, have the grace to stand still.”

“There’s a g–”

He shakes my arm. “Your Mum’s being buried, Taylor. Stand still.”

Frozen by Dad’s anger I watch him approach. Tears blind me and when I can refocus his face looms above mine. I can’t stop myself flinching when he grabs my hand. Ice spikes into my arm and I jerk.

He shows teeth like tombstones. “That was easy.”

I stare at my hand where a black stain has splashed me to the wrist. Dad gives me another shake and wordlessly I raise my arm to show him the Mark.

His shoulders shudder then he fixes his gaze back on Mum’s grave.

“Mum says the Darkness will come for me.”

“Your Mum isn’t here, I am and I’m not having my daughter going out and approaching strange people.”

“But what if the Darkness comes?”

“It won’t.”

“Look at my hand.” Over the last couple of days the Mark has darkened. Now it looks like a hole through my palm.

“It’s just a skin condition.” Dad won’t meet my eyes. “You’ll be fine. If I have to lock you in your room I will.”

“You have to let me out. It’s school tomorrow.”

“We’ll see.” Dad rolls awkwardly in his chair towards the living room.

I lie in bed and stare at my hand. I can’t take my eyes off it. The Mark seems to grow every time I look away.

I know the ghost is waiting outside. I’ve seen him. At least when Dad lets me out he’ll be right there. But I’m afraid it might be too late by then.

A compilation CD is playing on a loop. My ears are tuned into the sound rather than the song. I’m terrified that the noise will suddenly cut out. I know that means the Darkness is coming.

I hear the mechanical rumble of Dad’s stair lift. Then it falls silent. My heart stops.

It’s here!

No, my music is still thumping loud as ever.

My heart stutters back to life and I clutch my chest as the stair lift coughs and continues to climb.

Finally Dad rolls into my room. I lie with my back to him and refuse to turn.

“Taylor, it’s time to get up.”

“A-are you going to let me out?” Hope trembles in my voice.

“No.” The carpet shushes as Dad comes nearer. His hand falls on my back. “This is for your own good, when you see there’s no Darkness coming, you’ll be able to get better.” In the periphery of my vision I see him pick up The Tale of Oh-Fa and remove it from my bedside.

Still I cradle my fist under my chin and refuse to speak. My skin is numb where the Mark stains it. When the Darkness comes will my whole body feel the same way?

“Taylor, come to the kitchen. You have to eat something.”

I shake my head.

“I’m angry with your mum, you know.” His voice is low and I almost look at him.

“Why?” My eyes fall on a shadow on the wall and I jerk. Is it moving?

“She’s done this to you with her horror stories. I should have been stronger that day, when it all started for you. I should have taken you away.”

Staring through the dawn-brushed window I realised I was looking at the spot the ghost had occupied for those three weeks after Mum’s funeral. During the final week I didn’t eat or sleep. Dad considered hospitalising me, I know he did. But finally he relented and let me out. Luckily the killer had been easy to find and Mark, even for a young teenager, so the Darkness hadn’t taken me. It had been close though. Everywhere I looked the shadows had been trembling.

So I had around three weeks to find Justin and get him to take me to his killer.

The school corridors were quiet once more. Hush reigned where usually there would have been pre-class chaos. One of the boys from the lower school jostled me as he ran through the common room. I caught him with a frown, but he had already stopped dead with one foot raised in ridiculous apprehension. He licked his lips as he slowly put down his foot and edged between the static groups. I watched him break into a self-conscious jog as soon as the double doors closed on his back, then turned as Hannah closed her hand around my elbow.

“You’re here early.” She dragged me towards an unoccupied table. “You missed the police yesterday. They talked to us in assembly, then Tamsin went home.” She lowered her voice. “Justin's missing. Isn't it awful?”

I nodded as we skirted the news-thrilled whisperers. Then I stopped, pulling Hannah short.

Tamsin had leaped to her feet and now stood over her hags. Her blonde hair was in its usual perfect waves, but her make-up was just that little bit off, giving her face the expression of a plastic doll left too long by a roaring fire. The reddening of her cheeks added to the effect of heat-blast Barbie.

“What would you know about it?”

She slammed her hand down on the table, making books jump. Her girlfriends avoided her eye and one in particular leaned from her wrath, so unbalanced it looked like she’d fall off her chair any second.

Tamsin spun to face the rest of us. “You’re all thinking it, aren’t you? That he’s run away and it’s my fault because he was my boyfriend. Well, you’re wrong.” She tottered away from the table, fists clenched. “Anyone else want to say it? Come on.” Her eyes narrowed as she zeroed in on Hannah and me: somehow the only others standing in her eyeline. “How about you, Oh?” She angled towards me, propelled by fury. Her face thrust against mine, her hot breath slightly sour. This close I could see how the whites of her eyes had become yellowed and bloodshot. They were eyes I’d seen in the mirror often enough. She had been crying. A lot.