At the stairs I looked back. “That was easy.” Hannah was right; something was off. I scanned the room.

The boys were lined up like they were at a club but James’ blond hair hung messy and unkempt and instead of his usual alert posture he was slouching with his muscles bulging unflatteringly. Harley, whose jackal laugh could usually be heard wherever you were, was silent and he had dark circles under his eyes. Even Pete’s shirt was already hanging out of his trousers.

Only Justin looked together, but he was watching Tamsin like he was on a diet and she was dessert. Normally they’d be all over each other but Tamsin was looking everywhere but at Justin.

So that was why we’d got past so easily, the “it” couple were having a fight.

I nudged Hannah as one of the girls said something to Tamsin under her breath and she ran to the toilet.

“What’s gone on there, d’you think?” Hannah cocked her head at the fleeing queen bee.

I shrugged but didn’t take my eyes off Justin. He watched his girlfriend go, but made no move towards her.

As usual he stood a little bit away from the other lads. Five years on and he still lightly wore that sense of exotic newness he’d arrived with on his first day. Adding to the sense of slight unreality that always surrounded him, his eyes now darted restlessly from student to student, never stopping in one place. As his gaze landed on me, they narrowed and I couldn’t resist giving him the Loser sign.

“Hey.” He straightened up as if I’d shoved him and I lifted my chin. I didn’t really want to get in a fight with the jerk, not again.

“Come on, Hannah.” I grabbed her elbow and steered her up the stairs.

Justin’s voice rose above the general clamour of the common room. “Get back here, Oh.”

“I don’t think so,” I muttered and stalked away.

“I know you heard me. Turn round.”

I grit my teeth. Only a few more steps and we’d be outside Mr Barnes’ office. He won’t dare start anything there.

Year eight girls clustered at the top of the stairs. I used my shoulder to barge our way through. They moved slowly, glowering at us, but weren’t far enough up the food chain to say much.

A gap opened ahead, but before I could dive into it, my bare right hand was caught from behind.

A shock both familiar and unutterably terrifying ran up my arm.

Suddenly the signs hit me: the strained hush, the policemen, Tamsin’s upset. It hadn’t been a fight that had prevented Tamsin from meeting her boyfriend’s eyes.

I dropped Hannah’s elbow and turned.

Justin’s hand was locked around mine. The cold flesh of his palm was flat against my own. The darting of his eyes – he’d been looking for a sign that someone saw him. Too late I recognised his flickering gaze as the confusion of the newly dead.

I swayed as his wintry touch continued sending spikes of ice up my arm and pulled away before the chill bit me to the bone. It was too late. I stared at my hand in sullen comprehension. Swirling on the palm like a smear of black ink was a Mark.

How dare he do this to me?

As my brain struggled to get past the shock I stared into Justin’s dark eyes, those eyes that said he hadn’t yet come to terms with what had happened to him.

Great. Sometime over the weekend Justin Hargreaves was murdered… and now I have to avenge the idiot.

A younger boy was standing behind Justin.

He glared at me. “What’s your problem?”

“I'm not looking at you,” I snapped.

“Freak.” He stepped around me and I turned to Hannah. “You go ahead. I’ve left my homework in the locker.”

Hannah headed for the classroom, unaware that she was leaving me with the ghost of my worst enemy.

“Outside.” I spoke from the corner of my mouth, whirled and headed back down the stairs.

At the bottom I stopped. Mr Barnes was standing in the common area with two policemen at his back.

“We’ll speak to each class individually,” he was saying, “but just so you know, one of our students has disappeared. If anyone hears from Justin Hargreaves, please contact the police. If you know anything about what’s happened to him, if you aren’t comfortable talking to the police, come and speak to a teacher and we can do it for you.” He glanced back and one of the policemen nodded. He was holding his hat like a shield.

“You couldn’t have come out of your office five minutes ago?” I muttered.

Mr Barnes looked seriously at each group of students then shook his head sadly. “The bell’s about to go, you can start making your way to your classrooms.” He turned and left. I waited for a moment to make sure he was gone and then marched to the door.

Justin fell into step with me and I grit my teeth. Once in daylight, I hesitated.

“Where’re we going?” Justin’s voice in my ear left no impression on the air, no breath on my skin. Still I jerked back, not wanting to be in the same airspace.

I held my hand over my mouth. “Somewhere private so we can talk.”

“You don’t want to be seen talking to me? It can only improve your reputation.”

I whirled on him and one of the younger kids who took my bus stumbled over the step in his hurry to get away.

“Shut up if you aren’t going to help.”

He shrugged and gestured. “Bike sheds?”

I glanced contemptuously in the direction of his pointing hand. “Full of losers getting a smoke before class.”

My rucksack started to slide down my shoulder and I nudged it into a more comfortable position. As I did so I remembered my mobile. We weren’t supposed to use them, but if I stood at the bus stop people would probably leave me alone and I could talk to Justin without looking like a nutcase.

I set off towards the gates and pulled the phone free.

With the scratched bus shelter propping me up, I squinted into the reflection of the sun as it glared from a multi-storey office block. Rather than look at Justin, I lowered my gaze to watch the cars and taxis belch past.

A few late students were sprinting from the tube. As they passed, each looked at me curiously, wondering why I wasn’t running with them, trying to get into class before registration.

The number ten rounded the corner and I felt in my pocket for my pass. I hadn’t intended to bunk off school, but I couldn’t stay now.

As the bus pulled up I looked around. There was no one to stop me getting on.

The doors opened with a mechanical hiss. I gestured at Justin to follow and climbed on board.

As I swiped my Oyster card the driver glared disapproval. Almost too late I remembered the school speaking to the bus company about truancy. Quickly I groaned and clutched my stomach. With a shake of her head she waved me past.

The bus was practically empty, the work rush ended. Holding the phone to my ear I dropped onto the back seat. Justin sat in the seat behind.

“You’re skiving,” he muttered delightedly.

Hannah was going to kill me. She hated it when I left her alone at school. I glared out the window as the distinctive mix of architecture zipped by in jerks and starts. Finally I gave up and looked at Justin. He was slouched along his own seat, one arm draped over the back.

“So, what happened to you?”

He tensed. The humour left his eyes and he sat up. He knitted his lean fingers. “Would you believe I was starting to think no one could see me?” He stopped. “It’s stupid.”

“Why do you care what I think?”

He stayed quiet.

“So, what do you think now?”

He swallowed. “I… I don’t know. It’s some sort of trick, right? Everyone’s pretending not to see me and those policemen have to be in on it.” He thumped the seat and raised his voice. “This isn’t funny, guys.” He turned around. “I’m on YouTube, right?”

“You’re dead.”