Jarrow stopped talking as Arthur suddenly whimpered in pain and clapped his hands to his head. He felt as if a missile had struck the centre of his brain, exploding into a vast array of memories. Images, sounds, smells, and thoughts reverberated everywhere within his skull, so many that he momentarily felt disoriented and sick. Every significant memory from the day he lost his yellow elephant to the approach of the three Bathroom Attendants was overlaid all at once in a crazy mishmash of instant recollection.

The pain disappeared almost at once, and the memories slowly retreated deeper into his head, sorting themselves out as they went, though not in perfect order.

However, he did know who he was and what had happened, and that he was in great danger from Sir Thursday.

‘Are you all right, Trooper?’ asked Jarrow.

‘Yes, sir,’ whispered Arthur.

‘Memory pain,’ said Fred. ‘I punched myself in the mouth once because of it. Got a fat lip. Did you remember anything useful, Ray?’

‘Maybe,’ said Arthur guardedly. He was in a tough position. He wanted to tell Fred everything, but that would only put his friend at risk as well. ‘I’ve got a few more things to think through anyway.’

‘You two rest,’ said Jarrow. He stood up, loosened his tulwar in its scabbard, and began to pace quietly around their small island. ‘I’ll keep watch.’

‘Don’t you need some rest too, sir?’ asked Fred.

‘I have much to think about,’ said Jarrow. ‘And I do not need to rest yet. Piper’s children need more sleep than drafted Denizens, and those Denizens need more sleep than regular soldiers like myself, who were made for the profession of arms by the Architect. But even I need to sleep more than our red-eyed comrades here, who sleep only in their stables and then no more than once a seven-day. I will rouse you before the dawn, or if there is the suggestion of trouble.’

There was no alarm in the night, though Arthur woke several times, disturbed either by some night noise or by a twinge of discomfort, born from sleeping on the ground with only a saddle for a pillow and a rough, felted blanket for bedcovers.

Arthur was woken properly by Jarrow before any sun was visible but as the higher stars began to fade. Without the need for breakfast, and being forgiven shaving as they were in the field, the trio quickly saddled the Not-Horses and went on their way, the two boys working hard to bear in silence the aches and pains that had come from the previous day’s ride and their night on the ground.

Arthur did not spare too much attention to these pains, or to the swamp he was travelling through. His mind was fully occupied thinking about what he was going to do, and what Sir Thursday might do to him. The Trustee had to know who Arthur was, because either Lieutenant Crosshaw or Sergeant Helve would surely have reported his presence. Or possibly Sir Thursday might have known all the time and had Arthur drafted on purpose, rather than by bureaucratic accident.

But why would Sir Thursday summon all the Piper’s children in the Army to the Citadel if he only wanted to get Arthur? There had to be more to it, Arthur believed. There was also the question of what he was going to do if the opportunity presented itself for him to try to find the Will or get hold of the Fourth Key. Should he take it and put himself at risk of retribution? Or should he be a good soldier and follow orders and not give Sir Thursday any excuse to put aside Army Regulations and do something horrible to him? If he just tried to be a good soldier, he might end up having to serve his hundred years, and he’d never get home –

Home. The Skinless Boy. Leaf. The –

‘The letter!’ Arthur suddenly said aloud, slapping his head again. He’d just remembered the letter from Superior Saturday, the one threatening his family. As Ray, without his proper memory, he’d dismissed it as a hoax. But now that he remembered everything, it brought home everything he had feared would happen with the Skinless Boy.

‘We must be quiet from here,’ ordered Jarrow, wheeling his horse to address Arthur and Fred directly. ‘The pass ahead should be clear, but we cannot count on it. Close up on me and ready your swords. We will charge through if the way is blocked.’

Arthur rode close enough to almost touch knees with the lieutenant, while Fred did the same on the other side. If they had to charge, they would do so as a tight mass of Not-Horses, a wedge that should punch through any New Nithling ranks that stood against them.

As they advanced, Arthur looked around properly for the first time in at least ten minutes. They were leaving the swamp, heading west, and the tile ahead was dominated by two rocky hills, with a shallow gorge between them that was perhaps half as high. The rough road they were on led into the gorge.

‘Can’t we go around?’ he asked. He couldn’t see anything too formidable to the north or south.

‘There are mud pools to the north today,’ said Jarrow, tapping his Ephemeris. ‘And thistle-scrub south. Very slow for the Not-Horses. This way is somewhat steep, but the road is wide and good. Beyond the pass, there is grassland and a bucolic village. After that is the easternmost fixed tile, which is the Eastern Water Defence. If we are not way-laid, and the water defences are dry, we should be at the Citadel by late afternoon.’

They were not waylaid, but well before they saw it, they knew the Eastern Water Defence was not dry. It had been flooded, and some of its water was spilling over into the adjacent tile, running down the main street of the bucolic village, a lovely but uninhabited collection of narrow lanes and charming houses that surrounded a large village green bordered by several pubs, a blacksmith’s forge, four or five small shops, and an archery range.

‘Was there ever anyone here, sir?’ asked Arthur as the Not-Horses waded up to their fetlocks in the water streaming down the main street, their noses held high to show their dislike for the stuff.

‘Not permanently,’ replied Jarrow. He spoke quickly, and his eyes were never still, darting this way and that as he looked all around. ‘But in the past, whenever this tile came close to the Citadel, the White Keep, Fort Transformation, or one of the other fixed locations, the taverns would be manned and a fair established for the day. We should be able to see the Citadel in a minute. Once we are past these buildings.’

The road began to rise after the town, then levelled out again. There were stands of tall cypress at intervals along it, but the view was clear straight ahead. As they reached the flat, Jarrow stopped and gazed out, shielding his eyes with his hand.

Arthur and Fred did not look so much as stare, their mouths open wide enough to catch any small insects that might have been about.

There was a broad, mile-wide lake ahead of them, stretching north and south onto other tiles and on out of sight. Its eastern shore lapped the edge of the village tile, which was marked by a line of tall pines, many of them shorn of western branches.

Beyond the lake was a giant wedding cake of a fortress, spread over many miles. The outer line of angled bastions – which to Arthur looked like short, broad, triangle-shaped towers – formed the bottom of the cake, then a hundred and fifty yards in and fifty feet higher there was the second line, and one hundred and fifty yards in from that and up fifty feet again was the third line. Beyond that line was a hill of stark white stone, and on the hill was a star-shaped fort, each of its six points a bastion that held half-a-dozen cannon and perhaps two hundred defenders. Right in the middle of the Star Fort was an ancient keep, a square stone tower a hundred and fifty feet high.

A huge cloud of green smoke hung above the outermost defence line to the southwest.

‘Firewash smoke,’ said Jarrow grimly. ‘There must have been an assault sometime this morning. But I heard no cannons … we must be very low on Nothing-powder. We must go back to the village – we will have to build a raft.’

‘Can’t we signal the Citadel somehow?’ suggested Arthur. ‘Sir?’

‘I have no communication figures,’ said Jarrow. ‘None could be spared for me. If we signal with smoke or mirror, the New Nithlings may see it and send a raiding party. They must be established in force on the western plains. I have never seen a firewash cloud as big as that one.’

It was not as difficult to make a raft as Arthur had thought. They simply took a dozen barrels from the nearest pub, three of its doors, and a quantity of rope, cordage, pitch, and nails from the blacksmith’s, along with some of the tools. Under Jarrow’s direction, the barrels were lashed together, the doors nailed to the top, and the likely places for the barrels to leak smeared with pitch.

The raft was assembled by the lake’s edge, very close to the tile border with the bucolic village. Arthur was acutely aware of this, though he managed to stop himself from looking at the position of the sun all the time, and he didn’t ask Jarrow where the village was going to go at sundown.

But he got more nervous as the afternoon progressed. It was perhaps half an hour short of dusk when they finished, with the final touches being three oars from planks ripped out of the pub’s benches.

It was a fine-looking raft, but it didn’t look big enough for three Not-Horses, a Denizen, and two Piper’s children.

‘Get all the harness and gear off the mounts and onto the raft,’ said Jarrow. He too looked at the setting sun. ‘We’ll give them a quick brush and oiling before they go.’

‘Where will they go, sir?’ asked Fred. He had become very attached to his Not-Horse, who according to the name engraved on its steel toe-caps was called Skwidge.

‘They’ll find their way to friends,’ said Jarrow. He took the saddlebags off his mount and dropped them on the raft, which was now half in the water. ‘Hurry up! We have to be away from the tile border before the village moves!’

The sun was little more than a sliver, barely visible on the horizon, between the Star Fort and the Inner Bastion, when the last Not-Horse went on its way with a farewell whinny. Arthur and Fred hastily threw their brushes and cleaning clothes on the raft and started to push it completely into the lake.

‘Put your backs into it!’ urged Jarrow, once more looking at the setting sun. But the raft, despite being two-thirds in the water, with the barrels on the far end already floating, was stuck fast in the mud.

Arthur and Fred got down lower and really heaved, and this time Jarrow joined them. The raft slid a few inches but stopped again.

‘What’s that noise?’ gasped Arthur, in between shoves. He could hear a high-pitched whistling, like an ultrasonic dentist’s drill.

‘Tile moving!’ shouted Jarrow. ‘Into the water, quick!’

He grabbed Arthur and Fred and dragged them away from the raft and into the lake. Within a few steps it was up to the chests of the Piper’s children, but Jarrow kept dragging them on, even though Arthur and Fred had their heads back and were gasping for air, their feet scrabbling to touch the ground as their heavy Horde hauberks and gear threatened to drag them beneath the water.

Twenty-one

JUST AS ARTHUR and Fred thought they were going to drown, which was no improvement over death by dismemberment when the tile changed, the high-pitched whistle stopped. Jarrow stopped too and turned around, but he didn’t immediately head for the shore.

‘Help!’ gurgled Arthur.

‘Can’t reach the ground,’ gasped Fred.

Jarrow still didn’t do anything but stare back at the shore. Then he slowly dragged Arthur and Fred back out and dropped them next to the raft. After a frenzied minute of coughing and gasping, the two boys recovered enough to notice that the raft was intact – and the bucolic village was still there.

Jarrow stood near them, flicking through his Ephemeris, the pages held close so he could read them in the twilight.

‘The tile didn’t move,’ said Arthur.

‘No,’ said Jarrow. He shook his head. ‘But it should have. This is very serious. Only tectonic strategy has kept the New Nithlings from massing an overwhelming force against us for a decisive battle … We had best get to the Citadel at once!’

He threw himself against the raft with new fervour, weakly assisted by Arthur and Fred. This time, their makeshift vessel slid all the way into the lake and bobbed about almost as well as a proper boat. Or at least a proper boat that permanently suffered from a fifteen-degree list to starboard.

Though it was slightly less than a mile across the lake, Arthur and Fred were very tired before they had got halfway. Jarrow kept up a punishing paddling pace and would not let them rest.

‘Sir, if we could take a few minutes –’ Arthur began to ask.

‘Paddle!’ shouted Jarrow. ‘You are soldiers of the Architect. Paddle!’

Arthur paddled. His arms and shoulders hurt so much that he had to bite his lip to stop himself from whimpering, but he kept paddling. Fred kept paddling too, but Arthur didn’t really notice. His world had become small, containing only pain, the paddle, and the water he had to cleave and push.

The moon began its shaky ascent as they approached one of the outer bastions that thrust out into the lake, small waves lapping the stone wall that faced the earthen embankment. The moonlight caught their helmets and hauberks, and that caught the attention of the sentries.

‘Who goes there?’ came the cry across the water, accompanied by the flare of a quick-match as someone readied a musket or small cannon to fire.

‘Lieutenant Jarrow of the Horde and two troopers!’ shouted Jarrow. ‘Requesting permission to land at the water-dock.’

‘Cease paddling and await our word!’

Jarrow stopped paddling. Arthur almost couldn’t stop, his muscles set in a repetitive pattern. When he did lift the oar out of the water and lay it down across the raft, it took several seconds to get his hands to unclench.

‘Advance to the water-gate!’