Gesturing at the mouth of a road on the other side of the thoroughfare, Trounce said, “Here we are again. North Audley Street. If we continue straight on, we’ll be back in old Grosvenor Square, with New Grosvenor Square overhead.”

“Bad memories,” Swinburne said. “Though they belong to my predecessor.”

“I suppose the commotion is what Grub was referring to?” Wells asked.

“Yes. Aboveground, the American Embassy is a burning wreck. Beneath it, some of the Underground’s ceiling has obviously fallen in. I hope there weren’t too many casualties. We’ll skirt around it. A little way eastward through the market then south into alleyways that’ll take us to Berkeley Square.”

“I’ve had unfortunate experiences in alleyways,” Burton grumbled. “Being held at gunpoint by you being one of them.”

Trounce laughed. “I recall I was masquerading as a fictional detective named Macallister Fogg at the time. A ridiculous farce. Did I ever apologise?”

“You didn’t need to. I thumped you on the chin.”

They walked through the market, passing stalls selling fruit and vegetables, meat and fish, clothes both newly made and second hand, pots and pans, brushes and cloths, tools and furniture; passing vendors of milk and tea and coffee, mulled wine and frothy ales, tinctures and pick-me-ups; passing tarot card readers and crystal ball gazers, palmists and phrenologists, astrologers who couldn’t see the sky and numerologists who probably couldn’t add up; passing four-armed jugglers and one-legged balancing acts, swan-necked singers and multi-limbed dancers, accordionists and violinists, deep-chested trombonists and bone-fisted drummers; passing emaciated beggars and obscenely curvaceous prostitutes, tousle-haired ragamuffins and shuffling oldsters, sad-faced young women and flint-eyed young men; passing vendors of corn on the cob and baked potatoes, winkles, mussels and jellied eels, roasted nuts and toffee apples.

It was as if Burton’s London had been revived in an outrageously distorted form and buried beneath the surface of the Earth.

They walked on until they were almost opposite the spot where Shudders’ Pharmacy had once been. There was no sign of it now, a slumping tenement having occupied the site.

“Here,” Trounce said, and led them into a narrow alley between two immense arching pylons.

Rats scampered out of their path.

Trounce used the heel of his boot to shove a pile of rotting wooden crates out of the way.

They moved on in silence.

Rounding a corner, they were brought up short when a headless man jumped out of a shadowed niche and brandished a knife at them. He was naked from the waist up and had a coarse-featured face in his chest. “I durn’t bloody care. I durn’t. I’d rather cop it wiv summick in me pockits than nuffink. Give me what yer got. Anyfink. Give me. Give me, or I’ll slice the bleedin’ lot a yer.”

Swinburne stepped forward. “My dear fellow,” he said. “You have been liberated. We are your saviours, not your enemy. Do not misdirect your newfound discontent.”

“Shut yer mouth yer bleedin’ midget an’ hand summick over.”

The poet sighed. “Then with regret, I have no choice but to give you this.”

He drew his pistol from his waistband. “Between the eyes. Stun.”

The weapon made a spitting sound—ptooff!

The man flopped to the ground.

“Well done, Carrots,” Trounce muttered.

“Poor blighter,” Swinburne said.

Trounce led them around the prone form.

“He’ll wake up in due course,” the poet noted. “I can’t blame him for his actions. He’s waking from a BioProc haze; realising the unadulterated truth of his existence. There’ll be anger and violence before the people identify, and move against, their true enemy.”

They filed through a maze of twisting and turning rubbish-strewn passages, traversing a district that, in Burton’s time, had been among the most prosperous in the city, but that was now much how he imagined Hades to be: confined, hot, dangerous and seedy.

Finally, the group emerged into Berkeley Square. Once a smart area filled with the well-off, it now resembled a mist-veiled crater in the middle of a shantytown.

“You’ll recall this,” Swinburne said to the king’s agent as they reached the centre of the paved space. “Though not fondly.” He kicked the toe of his left boot against a metal manhole. “Not exactly the same one, but close enough.”

Burton remembered and felt himself go pale. Last year, or rather, three hundred and forty-three years ago, he’d climbed down through a very similar metal lid into Bazalgette’s sewers, there to have a final showdown with an invader from a parallel history.

“The sewer was rebuilt and greatly expanded many years ago,” Swinburne said, “but it still follows the course of the Tyburn River. This hatch leads down to a maintenance tunnel that runs alongside it. It’s a lot drier than the sewer but also a lot narrower.”

“We—we have to go—to go even farther underground?” Burton stammered.

“I’m afraid so.”

“We’ll be all right,” Trounce said. “As long as we don’t run into any spider sweeps.”

The diameter of the tube was such that Burton, the tallest of the group, had to bend his back in order to pass along it. The physical discomfort only added to his distress. He felt like he was in his grave. The weight of the double-layered city pressed down, liable to crush the conduit at any moment.

His jaw was clamped shut. The muscles at its sides flexed spasmodically. Sweat trickled from his brow, and his legs were trembling so much he felt sure his companions must notice.

He said nothing, just followed Trounce, putting one foot in front of the other, holding his arms out and letting his fingertips slide along the inner surface, keeping his eyes half shut and mentally chanting, Allāhu Allāhu Allāhu Haqq, which, unfortunately, quickly turned into, I am I am I am trapped.

The maintenance tunnel was dark. Trounce had produced a small mechanical torch from his pocket and with this was illuminating their path, but the blackness retreated only a little way ahead and rushed in to follow closely at their heels.

Don’t let that light go out! Don’t let it happen!

Finally, Burton couldn’t hold his curiosity at bay any longer and had to ask, “Algy, what are spider sweeps?”

“Children who’ve been genetically adapted for the purpose of keeping pipes such as this clean,” Swinburne answered.

“Children,” Burton murmured. “Good.”

“Good at their job, yes,” the poet agreed, “on account of the venom they spray to dissolve whatever dirt their coat of razor-sharp spines can’t scrape off.”

Burton’s mouth went dry. “Nevertheless, they’re just children.”

“Oh yes. There’s none above the age of ten.”

“Excellent.”

“Because the younger ones eat the elders.”

“Oh.”

“They’re extremely aggressive.”

“Uh-huh.”

“And territorial.”

“I see.”

“And, I daresay, with the effect of the nanomechs wearing off, they won’t hesitate to attack us.”

“Thank you for alerting me.”

“Beneath their spines, they’re armour-plated. I should think our bullets would just bounce off them.”

“That’s unfortunate.”

“I’m thankful to be as small as I am, really. I’m just a morsel. A crumb. I wouldn’t want to encounter them if I was a big lump of juicy meat like, for example, you are.”

“That’s quite enough, thank you.”

“Don’t you want to hear about their extendible mandibles?”

“No, I think I get the picture.”

They continued on through the cramped tunnel.

Burton tried to imagine open skies, wide Arabian vistas, and distant mountains. Instead, his mind delivered a remembrance of Boulogne and Isabel. He tried to dismiss it, but each wave of claustrophobia brought it closer.