There was a knocking on the door. Rousing himself out of bed, the doctor came down to see what the bother was. A man stood in the rain, his cloak wrapped tight, his hood up. It was the overseer of the largest and most important fortress in the region. The doctor blinked. Looming out of the darkness, the overseer said:
"There's an emergency. Please come with me."
"An illness of some kind?" the doctor enquired, as he pulled on his boots and looked for his umbrella.
"Not exactly. You might call it an accident."
The doctor followed the overseer out into the night. A sedan chair stood on the road. One of the waiting runners helped them climb inside. There was plenty of room within and the doctor and overseer sat opposite each other. The doctor remarked:
"I thought sedan chairs only carried one."
"This is an extra big model," the overseer answered. "The fortress is too distant for one pair of runners to reach without a rest, so when they are exhausted, they will exchange places with us. And when we are exhausted, it'll be our turn again to be carried. And so on. This is not only fair but very efficient."
The doctor huffed. He hated running at the best of times, let alone while carrying a heavy object.
"What can I expect when we arrive?" he asked.
"I prefer not to give details now. The entire fortress is affected. You'll see it all for yourself."
The doctor frowned. He ruled out an outbreak of plague, because the overseer had denied there was any illness involved. Had an inner wall or tower collapsed, crushing people? This was unlikely. The edifice was too solidly constructed. It was the only impregnable fortress in the realm. Structural damage was unthinkable.
"Are lives at risk?" the doctor pressed.
"In a manner of speaking." The overseer refused to say more on the subject. He turned and gazed out of the window and nodded to himself at each bend in the rutted road.
The doctor looked out of the same window. The rain had stopped and the moon was breaking through the clouds. The summit of every hill they passed was crowned with a castle, for this was a land of castles, and the grey stones gleamed like giant teeth. One castle even seemed to be grinning, an odd optical illusion.
"Are there any hills without castles?" he wondered.
The overseer turned sharply. "At least a dozen to the north. There is still adequate space for new defensive buildings." His tone was so strident that the doctor suspected he had touched a raw nerve. But how? It was a harmless enough question.
"Well that's good to know," the doctor said.
The road curved into a forest. There were castles here too, half hidden by stunted trees, many of them in ruins, charred from old fires or smashed to fragments by siege engines. Some were occupied by bandits, highwaymen, strolling minstrels and other low types, who carried out no maintenance on their new homes.
At one point the road actually ran through the middle of a castle completely broken by a forgotten war. Even the few standing walls gaped with holes where invaders had forced entry long ago. The doctor found nothing astonishing in such destruction, for there truly was only one impregnable fortress in existence.
The sedan chair stopped and the overseer grunted. "Time for us to get out and carry the runners."
The clouds had vanished but the road was muddy and treacherous with slimy puddles. The doctor cursed as he shouldered his burden. He heard the runners inside joking with each other and he felt the shifting of their weight as they experimented with finding a comfortable position. He almost slipped several times.
They emerged from the forest and passed through a valley, climbing into the hills beyond. The road snaked through the peaks and a cold wind chilled the sweat on the doctor's brow. He was just about to give up and run the risk of refusing to run further, when the overseer abruptly gave the order for another exchange.
He climbed gratefully back into the sedan.
There were another two exchanges before they finally approached the impregnable fortress. The doctor had only seen it once before, during the coronation of the present king, nearly forty years ago. The edifice looked different from his childhood memory. The huge walls were weirdly distorted and bulged outwards.
The overseer hissed, "Very few people know about this. I trust you have enough sense to keep silent once the situation has been fixed? The price of gossip will be dreadful."
The doctor nodded and confirmed his loyalty.
The sedan chair crossed the drawbridge. The overseer dismounted and indicated for the doctor to follow close behind. They passed through a variety of entrances, each armed with a trap, each requiring a password, and the process was so convoluted it was more than an hour before they finally gained the main buildings.
The doctor endured another hour of cheating the defences, passing through mazes and dodging snares before they emerged into a small room in the central tower. Impregnable indeed! There was more to come. The overseer guided him down a lightless spiral staircase that seemed to be endless. Slippery steps underfoot.
At last there was some light, the splutter of a brazier from below, and the staircase disgorged them into a corridor. They followed this for another hour. Always the way was down.
"The bowels of the fortress," said the overseer. He paused before a tiny door. "We go through here."
"Where does it lead?" asked the doctor.
"It's a shortcut to the womb of the fortress, which is where you'll do your work," smiled the overseer.
It suddenly dawned on the doctor what was expected of him. "I don't have the right tools," he gasped.
"Don't worry. We have prepared everything. There is a block and tackle, wedges and chains, heavy lifting equipment of many sizes and shapes. And plenty of manpower."
"The fortress itself is sick!"
The overseer licked his lips. "I already told you it's more in the nature of an accident. We know what to do, but we need you just in case things don't proceed smoothly." Opening the door with a key, he gestured impatiently. "We're wasting time."
The doctor wriggled through the door and inched himself along a service duct until he emerged in a spherical chamber. He saw seven new castles, too well made to be models, pressed against the perimeter of the chamber and pushing the walls outwards, but there was space to pass between them because they were separated by miniature moats. Through the shallow waters waded many workmen.
"How did this happen?" cried the doctor.
The overseer blushed. "One night I heard a noise, a sort of inhuman grunting and sighing and moaning, and I jumped out of bed and peered through the window. I thought we were under siege, and so we were, but not in the usual way. Another castle had mounted the fortress and was performing carnal motions!"
"What a brute," responded the doctor.
"I can't honestly declare the castle forced itself on us. I suspect it was invited. Shameless!"
"But it left immediately after the deed?"
"Naturally. There was nothing distinctive about it and once it fled into the night there wasn't much we could do. We tried tracking it but a snowstorm covered the trail."
"And that was nine months ago?"
The overseer shook his head. "Five years."
The doctor nodded. The gestation period for castles was bound to be rather longer than for humans.
"How long has the fortress been in labour?"
"Nearly a week. It's driving us mad. The unborn castles are making no effort to leave the womb."
"Do you want me to help induce birth?"
"The workmen will do that. But if a turret snags on the side of the birth canal, we'll need your advice."
The doctor understood what this really meant. He had been brought here only as a consultant. In other words, a scapegoat, someone to blame and execute if anything went wrong.
He watched helplessly as the workmen looped lengths of chain around the castles and fixed these to pulleys. Ropes led off down an extremely narrow passage descending from the chamber. Somebody shouted something and unseen hands tugged on the ropes at the far end. The castles started sliding towards the passage.
Workmen stepped forward and applied their shoulders, heaving with all their strength. The sound was abominable. Wooden rollers would have helped but it was impossible to get them under the castles. The first castle reached the start of the passage and squeezed into it, pushing the walls back on both sides.
The mother fortress shuddered and rocked on its foundations. As the last of the seven castles was dragged and pushed into the passage, the doctor walked behind it, to check on its progress. Everything was fine so far. He felt the presence of the overseer next to him. The walls of the passage had gone slack.
They emerged into daylight, at the base of the hill on which stood the fortress, in the thick of the forest. Carts were waiting to receive the castles as they were born. One at a time these carts were driven off, sagging under the weight.
The doctor turned to the overseer. "What will you do with them now? Abandon them in the woods?"
The overseer exploded in fury. "What do you take us for? This isn't a fairytale!" Then he took a deep breath and calmed down. "No, there are seven hills far to the north with bare summits. We'll set them up there, to guard our northern borders."
"When they grow up they may resemble their father. It will then be possible to assign responsibility."
The overseer rubbed his tired face. "Maybe."
"Trust me. It's called genetics."
The overseer gazed up at the edifice behind them. "The important thing is that this affair remains secret. The security of our land is founded on the myth of the impregnable fortress. If word leaks out, it could mean the end of our culture."
Grimacing, he added, "None of us ever knew. I never even guessed. It's not impregnable at all!"
The doctor asked, "May I go now?"
The overseer nodded. "I'll escort you back to the sedan chair. New runners will carry you home."
The doctor bowed gratefully. Much later, as dawn bleached away the shadows, he roused himself from an unsatisfactory slumber and craned his neck out of the window of the moving sedan. He was looking for one hill and one castle in particular. A grin by itself wasn't real proof, of course. Only time would tell.