“It’d take a lot of rats. Trust me on that.” He splashed further on. The water was up to his knees and dragging at his coattails. “If you decide not to come, I’ll understand.”

Her whole body sagged. “I just don’t like rats,” she said miserably.

“Neither do I, unless they’re roasted. But I don’t really have a choice here: the tower’s that way and if I have to wade chest-deep in vermin to get to it, so be it.” He held out his hand, the one with all the fingers left. “Remember, what’s chest-deep for you is somewhere level with my forehead. Be grateful for that.”

She splashed out toward him and, as soon as she could, took his good hand and crushed it in hers. She closed her eyes.

“Get me through this, Okay?”

“Probably best we keep our mouths closed from now on. Any of this stuff gets inside us, we’re going to die horribly. Of course, I’ve more holes in me than a sieve. No situation so bad, it can’t get worse.”

They walked slowly through the water, Petrovitch batting the bigger floating debris out of the way and hoping that, as they crossed the side-junctions, they didn’t find a manhole whose cover had been lifted by the rising tide.

The tower grew closer, and at the point where they were going to have to start for the other side of the road, there were suddenly more people.

“Down.” He grabbed a half-submerged box and pulled it in front of them. As he crouched, he could feel the cold creep up to envelop his waist. Madeleine grimaced as she hunkered behind the debris.

She chanced a look through her lashes. “Who’s that?”

“Don’t know. Give me the goggles.” He held them to his face and pushed the box ahead of them. A black rat the size of a small dog scrabbled out of the cardboard flap and splashed into the water.

To her credit, Madeleine didn’t shriek. She looked at Petrovitch.

“Sorry,” he whispered.

Two figures were striking out for the tower from the other end of Piccadilly. Their grainy-green images pushed forward through the refuse-strewn sea. They made big bow-waves, almost running where they could, slowing only when their momentum threatened to lift them off their feet and send them floundering below the surface.

A giant splayed foot stamped into view, sending up a wave that threatened to engulf them. They bobbed like corks for a moment before regaining their stride. They made no pretense at stealth, shouting at each other in wild, high voices.

The pursuing construct stopped at the water’s edge, the second of its three feet checking its advance. A single arm dangled from the belly of its body; it reached out with it, claws from a wrecker snapping open as it descended.

It hesitated, then withdrew it.

“Sonja. It has to be Sonja.” Petrovitch stared again, trying to make sense of what he saw.

“They’re not shouting in English,” offered Madeleine.

“No. No, you’re right. Who the huy is that with her, because it’s not Chain.”

Whoever it was had Sonja by the arm. The taller figure was in front, the shorter behind. There was a hint of a struggle in their body language, in the way that one was pulling forward and the other seemed to be leaning back, resisting. But it could just as easily be explained by exhaustion on the girl’s part.

He passed the goggles back to Madeleine.

“We haven’t got another plan, have we?” she asked.

Petrovitch tutted. “Not anymore. Wait until they’ve reached the lobby, then we move.”

“They’re not looking at us,” she said. “We can move now.”

Madeleine used the pipe to steer the box ahead of them as they continued to use it for cover.

“You can touch it with your hands, you know. I guarantee it’s a hundred percent rat free.”

“Unlike everything else here.” She peered over the top. “They’ve just gone inside.”

Petrovitch shoved the box aside, which made a lazy circle and started to sink. “The Jihad is watching us, so look impressive.”

The tripod-construct turned its body toward them, tracking their movement through the water. When they reached the tower, it turned away, creaking toward Mayfair.

The water was up to Petrovitch’s navel by the time he peered through the demolished doors. Strip lights guttered overhead, and something was sparking in the ceiling, sending showers of electric rain across the submerged reception desk.

Bodies like bloated bags rotated slowly, turned by the current. Slick, furry shapes crawled over them and between them, squeaking feverishly. The air was sweet with decay.

“Blessed Mother. Save us.”

“The stairs up are on the far side.”

“They would be.”

“Give me the pipe.” He clawed his hand around it and started forward, poking the dead things aside. When he’d cleared an area and batted any rats away from the open water, he stepped into it. Madeleine stood on the backs of his heels and shivered, reciting the rosary prayer under her breath.

The lifts, half submerged, stood dark and empty. Water was welling out of them, making black bulges that oozed like oil.

“Nearly there.”

She stared at him, wild-eyed, and started again, “Hail Mary full of grace…”

The door at the side of the lift shaft was wedged open. The back of a chair peaked from the surface like an iceberg. Petrovitch propped the door wider with his foot and checked that there was no one on the stairs waiting for them.

“It’s quiet. Go.”

Madeleine pushed the chair further in and climbed up the first few steps. She had a tidemark of oil and slime around her hips, and her long legs were coated in dark ooze.

“That was disgusting,” she whispered.

Petrovitch stepped inside the stairwell and eased the door slowly back so that it wouldn’t bang, then he walked up to join her, water cascading from his coat. “I would say I’ve seen and done worse, but I can’t.”

“If I’d been on my own, I could never have done it.”

“Yeah. Know the feeling.” He sat down and lifted his feet above horizontal. Sludge dribbled out of his boots. “We’ve still got fifty floors to go. All the way to the top.”

Above them they heard the long echo of a closing door.

“All the way?”

“Every step.” He looked up, imagining the height of the staircase as it spiraled around the core of the building. “And we have to get to the Jihad before anyone else does.”

She held out her hand, and Petrovitch slapped the pipe into her palm.

“Thanks, but that’s not what I meant.”

“Oh. Okay.” He looked at both his hands, and picked the one without the missing digit. She laced her fingers through his, and they started to climb.

At floor ten—Petrovitch knew because he was counting, not relying on being able to interpret the kanji script—they were confronted by solid fire doors. The springs that held them shut were fierce, and these were what they’d heard banging from the ground floor.

“We do this quietly,” said Madeleine. She raised the pipe and pushed her shoulder against the crack in the double doors. There was a puff of air, the soft sigh of a seal being broken. She waved Petrovitch on, then let the door slowly ease back.

He went a little way on and listened intently. He thought he could make out two sets of footsteps. They sounded weary, grudging. He supposed his sounded the same.

He raised a finger to his lips, and pointed upward. They were on the same section of the stairs. Madeleine nodded slightly, as if vigorous movement might give them away.

They walked in silence from then on: not quite, though, for while Madeleine’s feet made no noise on the cold steps, Petrovitch’s boots did, no matter how carefully he placed them. He contemplated taking them off and slinging them around his neck, but going barefoot to his death was too much for him to consider. Better to die with his boots on.

At floor fifteen, they heard more doors closing. Whoever was with Sonja wasn’t being careful, and that was a good sign: they weren’t expecting company. Petrovitch raised an eyebrow heavenwards, and Madeleine leaned in close to his good ear.