His thoughts were interrupted when he collided softly with the back of the man in front. The man behind him piled into his back, too, and so on down the line as they came to a halt, almost without a sound.
“A gate?” the subaltern whispered. Looking ahead, over the shoulder of the man in front, Vatueil could just make out a broad grating filling the tunnel ahead. The single lamp was turned up a little. The water sieved itself between thick bars of what appeared to be iron. There was more whispering between the captain and the subaltern.
The tunnellers were called forward and were confronted by the grating. It was locked shut against a stout, vertical iron stanchion immediately behind. It looked like it was designed to hinge back towards them and then up towards the ceiling. A strange arrangement, Vatueil thought. All three tunnellers were ordered to light their lamps, the better to inspect the lock. It was about the size of a clenched fist, the chain securing it made of links thick as a little finger. It looked rusted, but only slightly.
One of the other tunnellers lifted his pickaxe, testing his swing and where the point might strike to break the lock.
“That will be noisy, sir,” Vatueil whispered. “The sound will travel a long way down the tunnel.”
“What do you suggest, bite it?” the younger officer asked him.
“Try to lever it off with the pry bar, sir,” he said.
The senior officer nodded. “All right.”
The tunneller with the pry bar brought it over his shoulder and wedged it under the lock while Vatueil and the other miner held it out from the grating, angling it just so to increase the effect, then, once their comrade had taken the strain, joining him to pull hard on the end of the bar. They strained for a few moments to no effect beyond a faint creaking sound. They relaxed, then pulled again. With a dull snap and a loud clank the lock gave way, sending the three of them falling backwards into the water in a clattering tangle. The chain rattled down into the water to join them.
“Scarcely quiet,” the subaltern muttered.
They picked themselves up, sorted themselves out. “No sticks or branches or anything against it,” one of the other men said, nodding at the foot of the grating.
“Settling pool further back,” another suggested.
Through the grating, Vatueil could see what looked like stony blocks in the path the water took beyond, like square narrow stepping stones filling the base of the tunnel. Why would you put those there, he wondered.
“Ready to raise it?” the captain said.
“Sir,” the two tunnellers said together, taking a side each, arms thrust into the dark water to pull at the foot of the grating.
“Heave, lads,” the officer told them.
They pulled, and with a dull scraping noise the grating hinged slowly up. They shifted their grip as it rose and pushed it towards the ceiling.
Vatueil saw something move on the ceiling, just behind the slowly moving grille. “Wait a moment,” he said, perhaps too quietly. In any event, nobody seemed to take any notice.
Something — some things, each big as a man’s head — fell, one glinting in the lamp light, from the ceiling. They smashed on the edges of the raised blocks beneath and dark liquid came pouring out of them as their jagged remains vanished into the moving water. It was only then that the men hauling up the grating stopped; too late. “What was that?” somebody asked. The water around the blocks, where the liquid had entered, was bubbling and fuming, sending great grey bubbles of gas to the surface of the water, where they burst, producing thick white fumes. The gas was rising quickly into the air, starting to obscure what view there might have been down the tunnel beyond.
“It’s just…” somebody started, then their voice trailed away.
“Back, lads,” the captain said as the fumes drifted closer.
“That might be—”
“Back, lads, back.”
Vatueil heard water sloshing as some of them started to move away.
The pale fog now almost filled the place where the grating had been. The men nearest it, the two tunnellers, stood back, letting go of the grille; it crashed down into the water. One of them took a step back. The other seemed transfixed by the sight, remaining close enough to sniff the milky grey cloud; he started coughing immediately, doubling up, hands on knees. His lowered head met a long silky strand of the gas at waist level, and he wheezed suddenly, standing up and coughing again and again. He turned and waved down the tunnel, then seemed to have a seizure. He fell to his knees, clutching at his throat, eyes wide. His breath rattled in his throat. The other tunneller moved towards him but was waved away. The fellow slumped back against the wall of the tunnel, eyes closing. A couple of the other men, also now near to the advancing cloud, started to cough as well.
Almost as one, they started to run, suddenly pounding down the tunnel, slipping and sliding and falling, the surface underfoot that had supported slow and steady steps with barely a slip turning to something like ice as they tried to run through the calf-deep water; a couple of them pushed past Vatueil, who had not yet moved.
We will never get past the narrow places with the bars, he thought. We won’t even make it up the slopes before them, he realised. The cloud was flowing up the tunnel at a moderate walking pace. It was already at his knees, rising to his groin. He had taken a deep breath as soon as he’d seen the dirty looking bubbles rising out of the water. He let it out, took another one now.
Some of the others were shouting and screaming as they ran away up the tunnel, though the principal noise was a frenzied splashing. The cloud of gas enveloped Vatueil. He clamped his hand over his mouth and nose. Even so, he could smell something sharp, choking. His eyes began to sting, his nose to run.
The grating would be too heavy, he thought. He stooped, felt for it, then with an effort he would not have believed himself capable of, lifted it in one movement and swung himself beneath it, stumbling through the water beyond as he let the grille go. His boots crunched on shattered pieces of glass under the surface of the water. He remembered to lift his feet for the blocks the bottles had smashed on.
The grey cloud was all around him like a cloak, his eyes were stinging and starting to close up seemingly of their own volition. He stepped quickly over the blocks, staggered into the water on the far side, then ran as fast as he could into clear air beyond, his lungs feeling as though they were about to burst.
Somehow he managed to delay breathing until he could see no trace of the grey mist either in the air or rising in bubbles from the water. He could hardly see, and the first deep, heaving breath he took stung first his mouth and then his throat all the way down to his lungs. Even the exhalation seemed to sting his nose. He took more deep, deep breaths, standing doubled over with his hands on his knees. Each breath hurt, but stung less than the one before. From up the tunnel, he could hear nothing.
Eventually he was able to breathe sufficiently freely to move without gasping. He looked back into the darkness and tried to imagine the scenes he might find walking back to the breach, once the gas had cleared. He wondered how long that would take. He turned and made his way in the other direction, towards the castle.
Guards found him hollering at the far end, where a vertical well shaft descended to a deep pool. Taken before the castle authorities, he informed them that he would tell them anything they wanted to know. He was just a humble tunneller who’d been lucky and resourceful enough to evade the trap which had claimed the lives of his fellows, but he knew of the scheme to tunnel to near the castle and set up some sort of compact but powerful siege engine, and additionally he would tell all that he could about the little he knew of the disposition, numbers and quality of the forces besieging the castle if they would but spare his life.