The man swung Zanna from side to side. The passengers were frozen in their seats.

“Stay back,” he said. “My colleagues’ll be here in a moment. I don’t want any trouble. We’ll take her with us and let the rest of you go. You know you can’t outfly a grossbottle, and you don’t want my associates joining us.”

“Airwaymen mercenaries?” Jones said, stepping forward. “No, I suspect we don’t.”

“You stay back!” the man said, and drew a sword with his free hand. Deeba screamed.

“Who you working for?” Jones said. “What do you want with her?”

“Shut up!” the man said, and yanked Zanna.

“Leave it!” Deeba said. “You’re making him angry!”

The man held Zanna by the throat. Jones faced him, his hands half-out, but he looked at the sword and held back. Obaday was huddling behind Zanna’s attacker, his head down, too terrified to move. The grossbottle was coming closer.

Suddenly, there was a grunt of effort, and something dropped from the ceiling. A body. A pale boy. The boy from the market. Stark naked. He fell out of nowhere, landed with a smack right in front of Zanna and the bearded man. The man yelped and staggered away— and backed his bum directly onto Obaday Fing’s pincushion head.

It was the blunt ends of the needles that jammed into his posterior, but they were still easily sharp enough. The big man leapt and shrieked, loosed his grip on Zanna, and swung his weapon.

Everyone moved. The boy gasped, reached for Zanna, missed, ducked, and dropped out of sight. Deeba shrieked. Jones grabbed Zanna. Obaday shouted, “It’s that boy again, that ghost. He’s in on it too!” He slipped and whacked the back of his head on a metal chairback, groaned, and lay still.

Jones swept Zanna behind him.

“Zann!” Deeba hugged her. They crouched behind the conductor. Zanna’s attacker was waving his sword.

The hands that Deeba had thought were crabs were on the floor between the man’s feet. And poking up from between them was the top of Hemi’s head, his two eyes staring at the girls, then abruptly sinking out of sight.

“What are you going to do?” the man shouted. “My friends are nearly here.” They could hear the grossbottle. “Give us the girl!”

“I’m a conductor,” said Jones, and stepped closer.

“I warn you!” the man shouted, and extended the sword into Jones’s path.

“I conduct passengers to safety,” said Jones. “I conduct myself with dignity. And there’s one other thing that all of us who take the oath learn to conduct.” He reached up and, so slowly his opponent didn’t respond, touched his forefinger to the point of the sword.

“Electricity,” Jones said.

As his skin touched the metal, there was a loud crack. An arc of sparks raced down the metal, into the big man’s hand.

He jerked, and flew back, landing on his back, dazed and shaking. His false beard was smoking.

Jones shook his finger: there was a single drop of blood where he had pricked it. He checked Obaday’s head. “He’ll be alright,” he said to Skool.

“It was that Hemi!” Zanna said. “We saw him in the market.”

“He was upstairs,” said Deeba. “He was looking through the ceiling…”

“He must’ve jumped on just as we set off,” said Jones. “Maybe he was the lookout for this charmer.” He pointed at the still-shuddering attacker. “That went a bit wrong, then, didn’t it?” He took handfuls of cord and ribbon from Obaday’s paper pockets. “Tie him up!” Jones shouted, and several passengers obeyed.

“I dunno,” said Deeba doubtfully. “Didn’t look like that to me…”

Jones looked around. “Well, he’s gone now, straight through the floor. Keep an eye out, alright?” Deeba and Zanna were looking about avidly, but Hemi was gone. “We’ll deal with that later. Have to focus now. That grossbottle’s coming. As quick as you can, stay down and hold on. Rosa! Evasion!”

The bus veered, pitched, and accelerated. Passengers shrieked. Jones hooked a leg around the pole and leaned out, notching an arrow into his bow.

With a growl of wings the grossbottle came close. Jones fired. His arrows thwacked into the fly’s disgusting great eyes and disappeared inside. The insect buzzed angrily but did not slow. The men and women it carried aimed a collection of motley guns. Their faces were ferocious.

One of them called out, “Prepare to be boarded!”

Jones drew his copper club.

“You maggotjockeys!” he yelled. “Leave my bus alone!” He leapt out straight at them.

Zanna and Deeba cried out. Jones flew through the air, shouting: “Un Lun Dun!”

“Look!” said Zanna. Jones’s belt was attached to the bus pole with bungee cord. The tether stretched and Jones grabbed hold of the howdah.

The startled raiders tried to aim at him. He kicked, then whirled his club at them, crackling with electricity. When the pirates rallied, Jones simply let go of their vessel. The elastic catapulted him back across the air into the bus. He somersaulted and landed perfectly.

Deeba said: “That was amazing… ”

“Tell me later,” he said, and ran up the stairs, the girls following.

“What was that you shouted?” Zanna said.

“A war cry,” he said. “Very ancient. The battle call of UnLondon.”

The top deck was cramped with pumps and gas machines. In one corner was a pile of dirty clothes. Jones aimed an enormous harpoon out of the rear window. He swiveled as the grossbottle veered.

The bus lurched, brought them almost face-to-face with the grossbottle itself. Jones fired.

A bolt shot straight between the fly’s enormous shining eyes. It jerked, its wings shuddered, and it dropped away.

“You got it!” said Zanna. The dirty body of the fly was spinning as it fell. Little dot-figures leapt from its plunging carcass, parachutes blossoming.

“And don’t come back!” yelled Jones.

“Conductor Jones,” Deeba said in a strangled voice. “Look.”

Far below was a patch of waste ground, dotted with crumbling buildings on which enormous insects busily fed. Two more grossbottles— one vivid blue, one a shining purple— rose above their revolting siblings and flew towards the bus, figures visible in the platforms on their backs.