Bert studied the surroundings of the carriage. It was a short, narrow space. Outside, he could see the skyline of the city rising and falling with the sway of the cables. There was a deep valley of sharp black rocks beneath them, and a waterfall spilling from the cliffs across the way.

“Stay a few paces behind me, Bert,” said the Professor. “I need to check on something.” He crept over to a doorway. There was a shadow at its base.

Bert was about to speak when the door burst open.

Cassius flew out of the compartment and tackled the Professor. There was a dull thud and a grunt of pain.

“Professor!” cried Bert. He rushed forward to help.

“Stay back,” yelled the Professor. He dropped his weight onto Cassius’s shoulders and heaved the quæstor down the corridor.

Cassius spun as he hit the wall. His hands flashed to his sides as he drew both his blades. “Thought you’d gotten away, Roberts?” he said as he lunged to attack.

The Professor drew his sword and performed a sweeping block. There was a sharp clang as one of Cassius’s blades went spinning from his hand.

Cassius snarled and swung with his other sword.

The Professor ducked, then rushed close and grasped the quæstor by the wrist. He turned Cassius’s remaining blade downward and a drove it into the floor.

“Not like training, is it?” said the Professor.

Cassius cocked his elbow and struck the Professor on the chin. He gave a swipe of his other arm and the Professor’s blade flew from his hand and embedded in the wall.

Bert again rushed forward but a well-aimed kick knocked him back.

Both men flew into a flurry of blocks and punches. The air whistled with the speed of their blows and the carriage shook. Bert struggled to keep his footing.

Suddenly Cassius dropped low and kicked. He caught the Professor’s heel and sent him staggering back. He hit the door of the carriage with a groan.

Cassius lunged forward to grab him.

The Professor gripped the quæstor’s arm and threw him full force against the door. There was a rending crash and both men disappeared through the opening.

“Professor!” cried Bert. He ran to the doorway and looked down. The drop below dizzied him for a moment but he forced himself to lean out.

He saw movement to his right. The Professor was hanging on to the side of the train. Cassius was luckier. He’d caught hold of a ladder, and was heading for the roof.

In that position, the Professor would be helpless.

Bert didn’t have time to hesitate. He grabbed the sword that was embedded in the wall and threw himself up over the doorway. For a sickening moment he felt the headwind lifting his feet out into space, but in a quick heave he managed to pull himself up onto the roof.

The cables creaked over his head as he crouched uneasily, trying to steady himself. The quæstor was only a short distance away over the carriage, shouting something that Bert couldn’t hear. The Professor was still clinging desperately to the carriage side.

Cassius turned to face Bert.

“Get away from him,” yelled Bert.

The quæstor held out his hands. “You don’t have to do that, Bert.”

Bert glanced down at the Professor. It was clear that he couldn’t get a foothold, that he was straining to cling on. “Get back,” said Bert. He took a step forward.

The quæstor didn’t move.

“I’m warning you,” said Bert.

Cassius crouched lower to balance himself against the swaying of the carriage. “It’s over, Bert. I don’t want to fight you, but I will if I have to.”

Bert gritted his teeth.

The quæstor took a step forward. “Give me the sword, or you’ll get hurt,” he said. “You’ve seen me fighting already. You know you’re no match for me.”

Bert refused to give in. The sword shook in his hand. He could still hear the faint voices of the soldiers in the carriages below, singing another song.

Cassius took a step closer. “This is your last warning.”

A hand shot over the side of the carriage. The blow hit Cassius’s ankle and sent him tumbling backward. His coat swirled around him as he rolled across the roof.

The Professor heaved himself up. “Well done, Bert.”

“Look out!” said Bert.

Cassius was running to meet the Professor. The carriage swayed under them, and both men staggered. The Professor seemed to find his balance just in time.

“Take that!” yelled the Professor, swinging a punch.

Cassius took the impact and crumpled. He fell heavily onto a wooden hatchway, and disappeared with a crash. There was a loud thump in the carriage below.

The Professor ran forward, then froze. “Oh dear,” he said.

Bert rushed over and peered down through the hole. Inside the carriage, a platoon of royal soldiers was staring up at them from around Cassius’s collapsed form.

“What’s going on here?” said a bemused-looking officer.

The Professor smiled. “We had a disagreement over a seat.”

“Stay right there,” ordered the officer. “Get them, men.”

“I think we’d better leave now,” said the Professor. He grabbed Bert and ran toward the front of the train. A pistol cracked behind them and a bullet hole appeared by their feet.

Bert raced as fast as he dared over the swaying roof.

The Professor took the sword from Bert’s hands and put it into his belt. He nodded to a ladder that ran down the side of the carriage. “Down there.”

“But we’ll be sitting ducks,” said Bert.

“We’ve nearly reached land,” said the Professor. He pointed down the line of cables to a large wheat field. “That’s where we make our exit,” he said. “If you’re up to it, Bert?”

He was already swinging down onto the first rung.

Bert winced as he followed the Professor down the ladder. His bruises were still stiffening from the last fall. “If I’m not, will you just throw me again?” he asked.

The Professor grunted by way of reply and lowered himself over the last handhold. The soldiers were shouting nearby. “Make sure to roll,” the Professor said.

Bert looked down. It was a longer drop than he’d expected—three times his height—and the train was moving fast. When he looked to his side, treetops flashed by at an alarming pace. “What if I … ?” He stopped speaking as the Professor dropped and landed with a rustle below.

“Come on, Bert!” yelled the Professor, his voice already fading into the distance.

Bert heard a shout of alarm in the corridor above. There were heavy footsteps heading toward him, followed by the drowsy voice of the quæstor.

“Wait,” shouted Cassius. “Don’t hurt the child.”

Bert swallowed. There were worse fears than a speeding fall right now. He looked down at the dizzying rows of wheat, gritted his teeth, and jumped.

He hit the ground and sank into the wheat with a dull crunch. His head felt cloudy for a moment. He saw a pair of pale orbs peering out at him from a sea of darkness, and at the back of his mind he heard the angry voice of Prince Voss, yelling: “Find the boy! Find the boy!”

“Bert,” called the Professor. “Come on, we’re not clear yet.”

Bert shook away the vision and started running.

Stalks of wheat poked through his clothes. The short stubble growth on the tracks of the field pierced his shoes and cut like splinters. But there was no chance of slowing down now. He kept his head forward and followed the Professor as they raced over the open space. He could hear the voices of soldiers in close pursuit. A whole troop of them seemed to have leapt from the train.

The Professor stopped suddenly.

“What is it?” asked Bert.

The Professor pointed ahead, where the field sloped down abruptly into a hollow that joined the boundaries of a large industrial complex. A thick smog hung over their view, but Bert could make out the jutting shapes of construction works and a tangle of wooden housing.

“The port’s down there,” said the Professor.

“Which way do we go?”

“Straight through that factory.” The Professor shot forward and began to bound and stumble down the steep bank into the smog.

Bert followed as fast as he dared, but his momentum soon took over, and he tumbled and rolled until he arrived at the bottom of the slope, caked in grass and mud. The Professor picked him up and helped him over a low metal fence. They landed on hard gravel. There were great vats of water on either side of them, with large crane-like girders hanging high above. A steady silver rain fell into the vats from a line of buckets, making a hissing and crackling sound as it hit.

“Bullet works,” said the Professor. He gestured to the machinery as he ran, apparently enjoying himself. “It’s clever stuff, Bert, for nonmagic.”

Bert didn’t have any breath left to respond. He pulled a stray stalk of wheat out of his collar and concentrated on moving his aching legs.

A workman up ahead yelled at them, and the Professor quickly cut between the vats and led Bert to a large hangar. “Keep up,” he said.

“I’m trying,” panted Bert. His feet were lightened by fear. He could hear angry voices around the yard as they passed, calling out warnings or asking what they thought they were doing. They ran beneath a vast metal hull, ducked through a shower of orange sparks, and arrived at a heavy latched doorway. The Professor knocked the latch open and beckoned.

Bert went inside and looked around. There was a straight corridor that led to the streets of the port. He was running for the light when a figure stepped into view at the end of the corridor. The figure was quickly joined by another. They were carrying swords.

“Soldiers,” cried Bert.

“Quick,” said the Professor. “Go right.”

Bert tried a door by his side, found it unlocked, and ran through. The Professor followed close behind. They passed over a metal walkway, then down into a room filled with rubbish. The room ended in a series of large metal slides. There was no time to think. Bert jumped into the nearest shaft and slid down. His stomach lurched for a moment, then he hit the earth with a crunch and rolled onto his back. He was outside, in a pile of brittle clay and dirt. All around were stacks of waste metal, papers, and manufacturing materials. It was all strangely familiar to him.

“Damn,” said the Professor. “We’re in the ratway.”

Bert looked around and nodded. Somehow he knew this place. Vague memories of early childhood came back to him—dark times after someone had died, hiding in the shafts of the kilnworks, listening for someone returning. “Follow me,” he said. There were doorways and tunnels cut into the rubbish. A whole network of slums bordered the factory.

“You know your way?” asked the Professor in surprise.

Bert didn’t say anything. He climbed up a flight of loose steps carved into the shale and cut through a tunnel made of rusted cans. At the end of the short enclosure he reached a straight, narrow path that weaved between two metal fences. He could hear soldiers and workmen yelling to one another from around the yard. But he wasn’t afraid of them here.

“Bert, do you know where we’re going?” said the Professor.

Bert slowed his pace and crouched as something rattled the fence to his left. He heard a group of boots crunching through hard clay.

“There’s a path here,” shouted a soldier. “Let’s climb up.”

Bert grabbed the Professor’s sleeve, popped open a slat in the opposite fence, and ran through a maze of rotting wooden posts. The rubbish closed in around them as they ran, making an almost complete tunnel. They emerged at a flight of steps.

“Well done, Bert,” said the Professor, beaming.

The steps took them to a rickety rooftop overlooking the port. Bert caught a glimpse of docked sailing ships and the lazy shapes of airships floating over the waves.

There was a wooden bridge connecting them to the next rooftop. “This way,” said the Professor. “They should be able to pick us up from here.”

“But it’s a dead end,” said Bert. He could hear officers yelling out orders from close behind, and soldiers calling in response. The troops seemed to be all around the block.

Pistols fired from the street below.

“Keep your head down, and keep up,” said the Professor. The bullets cracked as they passed. Bert ducked and ran with the Professor. They crossed over the bridge.

Ahead of them was a long, flat roof.

“We can’t stay up here,” said Bert.

“Do you hear that?” called the Professor over his shoulder.

Bert shook his head. His thoughts were filled with the volleys of gunshots and the drumming of his own heartbeat. “Hear what?” he asked.

“You’ll see,” said the Professor. He crouched, pulled a brass tube from his pocket, and unscrewed the top. There was a crack like breaking glass, and thick red smoke began to pour out of the container. He held it above his head and then tossed it down onto the gravel nearby.

Bert coughed. “Is that a smoke screen?” he said.

“It’s better than that,” said the Professor. “It’s a signal.”

“What kind of signal?”

A deep throbbing sound that Bert had been vaguely aware of before now grew suddenly louder and more intense. He looked toward the ocean. A huge green shape loomed over the rooftops. It was an airship. The sound of the engine grew to a deafening roar as its shadow fell over them. The bow guns fired, sending clouds of blue smoke all around the streets.

“That’s the Lugalbanda,” said the Professor. “My ship.”

Bert was stunned. Even in the fear and excitement, he felt a sense of wonder stirring inside him. The craving for adventure that he’d felt as a small child came to life again for one brilliant moment. But just then he heard something behind them. A running figure appeared through the smoke on the rooftop, drawing a sword and making straight for the Professor.

“Look out!” yelled Bert.

The Professor spun and raised his guard.

The soldier’s weapon fell against the Professor’s parrying blade, sending white sparks across the rooftop. The Professor twirled his grip over his head and attacked.

The soldier ducked and thrust one sword forward while he blocked the blow with a dagger. His lunge missed the Professor’s stomach by inches. “Surrender,” demanded the man.

Bert felt a heavy impact between his shoulders and tumbled to the ground. An officer grabbed and pinned him. In another moment metal handcuffs were forced onto his wrists. “Let go of me,” he shouted in panic. He realized with a shock that there were soldiers all around. They raised their pistols and took aim at the Professor. Bert’s heart turned cold.

“Ready,” said the officer. “Shoot to kill.”

The Professor realized the danger too late. He knocked down the soldier he was sword fighting, then turned to see the row of weapons trained on him.

“Fire!” yelled the officer.

“No!” cried Bert. Time seemed to pass strangely. He felt a wave of energy in his palm and heard the rooftop creak beneath him. He placed his hand down on the rickety boards.

The rooftop exploded in a mass of dust and splinters.

He fell through the hole and the soldiers tumbled with him. A rotten wooden board snapped beneath his back and he fell again, hitting beams and debris as he went.

Then he struck the floor and lay still.

More soldiers were running over the rooftops above. Bert heard the clash of blades, and a strange swishing sound, like something flung through the air.

“He’s getting away,” shouted an officer. “Stop him!”

Bert caught a glimpse of the Professor swinging on the end of a rope. The airship soared away quickly, taking him well beyond the reach of the soldiers. It looked almost peaceful through the gap in the smoke. Then the wind changed and the view was obscured.

Bert was relieved that the Professor had escaped. But whatever elation he felt was short-lived. The soldiers were climbing out of the rubble around him.

“We’ve got him,” said one of the men. “He’s in here.”

“Put your hands up,” yelled a gruff voice.

Bert glanced around and saw that he was surrounded. Men were climbing through the window of the ruined wall of the building, training their guns on him.

He stood unsteadily on the crumbling wreckage, covered in dirt and debris, assessing his cuts and bruises. An upright beam seemed to offer a handhold, but a soldier pushed him away and told him to stand against the wall. “All right,” Bert said, raising his hands. “I surrender.”

It seemed unreal. He thought back to his cozy dormitory at school, his collection of toys and magazines, the pillow that had grown shaped to his head, and then further into the past, to a vague memory of his home as a small child, someone ruffling his hair and putting him to bed.

He wished he could remember them clearly, see their faces and hear the words they’d said, but it was like there was a barrier in his mind separating him from those memories. There was no familiar warmth to be found in the world anymore. The soldiers barked orders at him and seized his handcuffs. His stomach sank as they led him out into the sunlight and he saw Prince Voss standing with his arms folded. It occurred to him that he had made a terrible, irreversible mistake.