The sharp crack of a rifle shot jerked me out of my doze. In the fractions of a second it took my eyes to adjust to the faint light from the moon, all sorts of crazy thoughts went through my head. Was the shot from our side or theirs? Were they trying to get over the wall? What was going on?

"Got 'im!"

I ducked below the concrete parapet and crawled the dozen metres from my duty position to the nearby sniper's nest. If we were being attacked, I didn't want to be a target. I pushed aside the tarpaulin that covered Murchisson's hole, to be greeted by his stupid grin. "Got 'im!" he said again, and chalked a mark onto the concrete in front of him.

"Who? What?" I scrambled to the loophole and peered out into the darkness that filled the kill-zone, hoping to see something.

"One o' them, o' course," Murchisson said. He fiddled in the pocket of his battledress and pulled out a dog-eared notebook. "Need you to witness it."

"Witness what?"

Murchisson gave me a pitying look. "You stupid or what? The kill. I need you to witness my kill."

I grabbed a pair of night-vision binoculars from their hook, and rested them on the lip of the wall, their lenses poking out through a gap in the tarpaulin. There was a whine from the electronics, and the billowing curtain of darkness turned into a world of blurred, green-grey shapes. I scanned the scrub that ran between the wall and the forest, but I couldn't see anything.

Murchisson slapped me on the back of the head with his notebook. "Well? You gonna sign?"

I shook my head. "I can't see anything out there."

Murchisson lunged at me, jamming my face against the rough concrete of the wall. I grabbed at the binoculars, holding tight to their strap. "Sign," he hissed in my ear. "Sign or I'll fucking - !"

"Oy! You two! Shut it!" Lieutenant Grey's voice cut through the darkness. "What's going on?" I felt the sniper let go of me, and I pushed myself away from the wall.

"Just asking Boden here to sign my logbook, sir," Murchisson said.

I scrambled around so I could see Lieutenant Grey. She fixed her eyes on mine. "So it was you making that racket?"

"Movement in the K-Z, sir." Murchisson held out his notebook. "Acted in accordance with the SOP."

Grey held out her hand. "Give. I'll be your witness." She took the logbook and scribbled something in it with a pencil, before handing the book back to Murchisson. "There."

"Thank you sir." Murchisson saluted.

"Carry on. Boden - with me."

I followed the lieutenant away from Murchisson's domain, glad to be out of the claustrophobic blister of concrete. She walked confidently, her head held high. I kept mine down, still fearful of any possible retribution that might come our way. We made our way to  the sangar - a ramshackle structure made out of sheet metal and ballistic cloth - and entered its blood-red interior.

"It would have been easier if you'd just signed it," Grey said to me.

"But there was nothing," I started. Grey raised a hand and I shut up.

"I know," she said. "It was probably just a rabbit. Or a fox." Grey sighed. "But he did manage to bag a deer about six months ago."

I found it difficult to believe what I was hearing. "You signed off on those?"

"I did." Grey sat down on a folding chair and started to fiddle with her boots. "How long have you been here, Boden? A month?"

"Just under, sir."

"First posting?"

"Sir."

"Then you're still just a greeny. You'll learn." She pointed at another chair. "Sit." I grabbed the chair and did as I was told. "This is your two-year hitch, right?"

I nodded. "Doing my national service."

She laughed. There was no humour in it - just pity. "So you'll do your two years, then what? You'll go home, back to your shitty life, proud of having stood on the ramparts of civilisation. Well, welcome to the world, Boden."

I was not sure what to say. Grey must have taken my silence as a sign that I was listening, because she spoke again. "Nothing happens here. Nothing important. Maybe one of the billies sticks their nose out of the forest to see what's going on, but that's about the size of it. You know that we used to send patrols out there to see what they were up to? We stopped. It wasn't worth it. Either they told us nothing, or they stirred up trouble."

The lieutenant paused and fingered her neck under her collar. I tried not to stare, but my eyes were drawn to a thick line of flesh, barely visible in the red light of the observation post.

"Anyway," Grey went on. "We like it quiet here. So what if Murchisson likes to let fly at something and claim it as a kill? If we sign his little book, it keeps him happy and it keeps the brass happy." She looked at me, fixing me with her stare once more. "It could be worse."

I didn't want to ask how. "So - it's all a lie? Everything they told me in training?"

Grey shrugged and looked up at the metal ceiling, strung with cables. "Who knows? We keep to our side of the wall, and the billies keep to theirs."

"So, what am I meant to do?"

The lieutenant smiled at me. Unlike Murchisson's, this one had an element of sympathy. "Do your hitch," she said. "Obey orders. Find a way to cope. Dismissed, Boden. Back on duty. And don't let me catch you asleep - understand?"

"Sir." I left the sangar and made my along the wall, back to my post. On an impulse, I stopped and looked out into the darkness, towards the forest and the billies that lived in it. And I wondered exactly what lay on the other side of the wall.