“We don’t have any rockets,” said Tom miserably. After that last terrible air battle over London, when he had shot down the 13th Floor Elevator and watched her crew burn inside their burning gondola, he had vowed that the Jenny would be a peaceful ship. Her rocket projectors had been empty ever since. Now he regretted his scruples. Thanks to him, Hester and Professor Pennyroyal would soon be in the hands of the Green Storm.

Another rocket slammed past. It was time to do something desperate. He called again on Quirke, then swung the Jenny hard over to larboard and took her powering down into the maze of the mountains, flashing through the shadows of wind-carved basalt crags and out again into sunlight.

And below him, far below him and ahead, he saw another chase in progress. A tiny scavenger town was scurrying southwards through a cleft in the mountains and behind it, jaws agape, rolled a big, rusty, three-tiered Traction City.

Tom steered the Jenny towards it, glancing from time to time into his periscope, where the three Fox Spirits still hung doggedly on his tail. Pennyroyal gnawed at his fingernails and gibbered the names of obscure gods: “Oh, great Poskitt! Oh, Deeble, preserve us!” Hester turned the radio on again and hailed the fast-approaching city, demanding permission to dock.

A pause. A rocket struck steam and splinters from a mountainside thirty yards astern. Then a woman’s voice crackled out of the radio, speaking Airsperanto with a heavy Slavic accent. “This is Novaya-Nizhni Harbour Board. Your request is denied.”

“What?” screamed Pennyroyal.

“But that’s not-” said Tom.

“This is an emergency!” Hester told the radio. “We’re being chased!”

“We know,” the voice came back, regretful but firm. “We want no trouble. Novaya-Nizhni is peaceable city. Keep clear, please, or we fire upon you.”

A rocket from the lead Fox Spirit came winding in to burst just off the stern. The harsh voices of the Green Storm aviators drowned out the threats from Novaya-Nizhni for a moment, then the woman was back, insisting, “Stay clear, Jenny Haniver, or we will fire!”