Lorsson took point, lighting the way with his sword as we advanced into the doorway. Tradfast came next, and me at the back. It was colder here, and more terrible frescoes adorned the walls, but I tightened the grip on my sword and bit my lip. I had greater things to worry about. I had Airon to worry about. Cold sweat formed on my brow, and doubt in my mind. What if he couldn't be saved? What if my only friend was already dead? But the fire in my heart burned that doubt away. I thumped my chest. Airon had to be alive.

"There's a crossroads," said Lorsson. "Let’s wait here and see which corridor the sound came from."

I nodded, and closed my eyes to focus my hearing. There was nothing but the breathing of Lorsson and Tradfast, and its steady rhythm settled in my ears just as the smell of stale air did in my nostrils. Then I heard the sound again, a distant clank. It came from the left passage.

"Left we go, dwarves," said Lorsson, and he turned, pointing his blade down the corridor. Its mottled glow lit the passage before us, an ugly dapple of red and white against the painted stones, and at the distant end of the corridor, it lit a figure in armour.

"There he is!" said Tradfast. "A sol-"

Another clank came, this time from the right tunnel. I spun around, smacking my sword against the wall with a clang that overwhelmed the quiet of the tunnel and had me wince. A figure stood there, in plain clothes. Battered silver glinted from behind him. More than one, then. I sucked in a breath and steadied my sword.

"Lorsson! Tradfast! There's some here too!"

"Shit," said Tradfast, pointing down the front corridor. "More of them. We're surrounded."

"No," said Lorsson. "There's still the way we came. We can head back, fight them one by one."

I turned my head to look back and saw Lorsson was right; no figures loomed in the corridor we’d come through. I inched down it, keeping my sword point raised in front of my face.

"I’ll guard the back,” I said. “In case they try to surround us.”

“OK,” said Lorsson. “But don’t get too far away. We don’t want to get separated.”

“Tell me when to stop.”

I edged forward, squinting as far into the blackness as I could, licking salty sweat off my beard.

"Stop,” said Lorsson. “Are you sure there's no one there?"

The corridor was empty, inhabited only by the harbinger paintings baring their teeth at me from the walls. "I'm sure. How many are in front of you? Is Airon there?"

There was a short pause. "I'm sorry, Stony, I don't know what your friend looks like."

"He's there," said Tradfast, voice hoarse.

Airon! The thought of finally seeing him again sent a rush of liquid hope through my veins, like tingling wine. My heart, already beating quickly, doubled its pace. I turned around, but Tradfast’s bulk filled the corridor and I couldn’t see past.

“Airon!” I shouted, but there was no reply. “Tradfast, is he injured?” I needed to know he was all right.

“I can’t see clearly.”

“Well look properly then! Is he injured?”

Tradfast shot me a hard glare. “It’s too dark, and we’ve got more than just him to worry about. Just stay back, and make sure nothing comes from behind. Lorsson and I will sort the rest out. Airon will be fine, provided Buro’s told us the truth.”

I narrowed my eyes at him. “Don’t patronise me, Tradfast. I’m as much a part of this as you. You’d be dead if it wasn’t for me, twice over. Make sure you don’t harm Airon.”

"Like I fucking said, Stony, I’m not here to harm anyone. You can't do anything to help here, so just stay there and guard the back. They’re getting closer."

I drew a hiss in through my teeth. There must be something I could do. Yes, there was! I reached into my pocket and closed my hand around the cool hardness of the sapphire, feeling the smoothness of it. The gap where a chunk had been removed flashed green in the faint red sword-glow as I pulled the gem up to my face.

"Ghost King," I whispered. "Can you give us some light?"

Blue brilliance shone from its every facet and I shut my eyes tightly. I held the gem up so Lorsson and Tradfast could see clearly.

"Well?" I said. "Helpful? Can you see Airon properly now?"

"Yes," said Lorsson. "Thank you, Stony. Is your friend the blonde miner?"

"Yes!” I wished I could see for myself. "Airon!" I cried. "Can you hear me? It's Stony! Your friend! We're here to save you!"

But no reply came. Had the possessing priest took further root in him, like a kind of monstrous soul-tumour?

"Captain Lorsson, how does he look? Is he injured?"

"He's not as bad as the others. His arms aren't hanging limp, at least. But..."

"But what? Tradfast, let me through!"

I squeezed past the enormous dwarf, grinding myself between him and the frescoes, chipping green paint onto my clothes but barely caring. I held up the sapphire and craned over Lorsson's shoulder.

There, was Airon, slightly behind a shorter soldier, marching forwards with the rest of the group.

"Airon!"

His hair was stained red over the blonde, and patches of it had fallen out, leaving chunks of raw bloody scalp showing. His hands and upper arms were covered in scratches and burns, and he had lost most of his fingernails. But his eyes were what drew my gaze. They were dead and empty, like a corpse's.

Lorsson took a step forward and I grabbed his shoulder plate, the harsh metal digging into my palm.

"Don't kill him," I pleaded.

"I'm not here to kill anyone, Stony. I know how to smack a dwarf down without injuring them."

"Careful," said Tradfast. "We could see how strong and desperate they were before. They'll stop at nothing to kill us."

"No," I whispered. "Not to kill us. They want this."

The possessed dwarves' eyes had turned to the brilliant glow of the sapphire. They knew what was inside it, and the King knew that too. Its light dimmed a little.

"Why don't you call on your King for help, Stony?” said Tradfast. “See if he's really on our side."

"No," said Lorsson. "It will be safer for the dwarves if we do this ourselves. I'm going to attack. Tradfast, keep your sword sheathed and hit them with it that way. I'm going to do the same. Stony, keep the light held up, but don't let them get to it."

"OK," I said. "Don't hurt Airon."

"I won't," said the Captain, and he advanced, sheathing his sword and snuffing out the runelight so the dull blue of the sapphire was all that shone. Tradfast grabbed my arm and forced it up, then pushed in front of me.

"Keep the gem there, and keep your eyes on the corridor behind." he said, glaring at me. “Actually, make sure you have one eye on the gem too. I still don’t trust this King you have.”

Then his thumping bulk obscured my sight of Lorsson and the possessed. I swallowed and turned, arm starting to ache. I desperately wanted to see what was going on behind me, but I had to keep my eyes on the other end of the corridor.

So I focused on sound. Lorsson's armour made a steady clank as he advanced, which was then joined by the grate of broken metal against broken metal as the possessed soldier ahead of him increased his pace.

"Give us the King," came a rasp, eerily like that of the outsiders down in town. “The monster who did this to us. Give him to us.”

"Never," said Lorsson, and there was a slow scraping as he pulled his sheath, sword encased within it, from his belt. “You did this to yourselves.”

The possessed rattled air through his throat, gurgling slightly too on what could only have been blood, and there was the stamp of metal on stone as he charged. Then came a swift rush of air and a thud, the sound of a body collapsing, then a yell from Lorsson and a further clatter of armour.

"I'll get him off you!" roared Tradfast.

"What's going on?" I shouted. I looked back, but could only guess what was happening in the tangle of bodies in the corridor. I caught a flash of Lorsson struggling against one of the possessed, who straddled him and clawed at his face. Tradfast was swinging at another possessed to try and get closer to the Captain. Adrenaline shot through me, but I seized the floor with my toes to stop myself running in. I couldn't stand just waiting here but I had no choice.

Airon's face appeared over Tradfast's shoulder. It was he who’d been attacking Lorsson.

"Airon!" I cried, but my friend, if he was buried in there, took no notice. Instead he bit deep into Tradfast's shoulder. “Tradfast! Don’t kill him! He’s not himself.”

"You miner shit!" shouted the Overseer and threw Airon bodily down the corridor. His body flew like so many loose limbs bound together, and landed with a crack somewhere in the distance.

"No!" I screamed.

"Yes!" screamed Lorsson in triumph, and the rasping cries of the possessed grew silent. There was the scrape of metal on metal as Lorsson crouched down and readied to sprint, but Tradfast grabbed him.

"There's no point chasing them," he said. "Let's deal with who we have."

"Airon!"

I shoved past Tradfast, slamming the Overseer against the wall with a strength born of despair, sapphire held before me like a torch. I no longer cared if something grabbed it. I needed to see my friend.

He lay at the back of the heap of possessed, who were a tangle of limp limbs, groaning and twitching feebly. But Airon neither groaned nor twitched. He was utterly still on the cold stone, a trickle of blood dripping from his forehead in a languid creek. In the strange blue light, the red seemed dull.

"Airon?"

I knelt beside him, panic rushing up within my like a flood. His skin was deathly cold to touch as I felt at his neck, pressing around to search for a pulse. But not matter where I pressed there was nothing but stillness, not a single pump of vitality in his veins.

"No!" Tears poured down my face as I tore his shirt down, looking to expose the great scar where the gem lay inside him. Maybe that was what kept him from breathing. Yes, that was it. If I removed the gem, all would be well.

There it was. I caught a noseful of the stench of rotten flesh as I ripped the weak fabric covering the wound. Deep within the purple gash, like some disgusting green parasite, sat a shard of gem, just barely glowing. I scrabbled at my hip for the dagger and closed my sweaty palm around its hilt. Trembling, I placed it over the cut and began to dig into the putrid flesh.

A stench like a dead thing from a thousand years ago hit me as I pried the slimy meat apart. But I barely flinched. I had to get to the gem. I had to dig this cancer from Airon’s flesh. The flesh came apart in so many slimy chunks, and I saw the shard was truly tiny. How could something so small have done so much damage? I dug the blade beneath it and pried it out, hands shivering with fear. I let it fall to the ground, and looked into Airon's eyes. He had to wake up. He had to.

But his eyes were dull, and dead.