Gooch said, “I recommend we postpone the philosophical pondering. Finish eating, gentlemen; Mr. Brunel has more to tell you.”

Half an hour later, he accompanied them to the famous engineer’s office, where Krishnamurthy and Bhatti were waiting.

As he entered, Burton noticed that Brunel had a large canister affixed to his back.

“It’s a battery,” the mechanical man explained. “Unlike the common clockwork servants, my body is powered by electricity. It has internal batteries but they require recharging every forty-eight hours, and this—” he jerked a metal thumb over his shoulder at the cylinder, “—does the job.”

Brunel gestured toward the armchairs. They settled, and he took the middle of the floor, facing them. In his clanging voice, he said, “You have met yourself, Sir Richard, but that other you was formed amid a tangle of particular circumstances that will occur in the near future—but in a world we do not inhabit. In the past of that world, a different Isambard Kingdom Brunel knew Henry Beresford, the Mad Marquess. Here, I never met the man. This idea—that there are multiple variants of our history and we are present in all of them—is difficult to comprehend, yet we must accept it as true if we are to understand our enemy.”

Burton murmured, “I’m hardly in a position to oppose the notion.”

“Indeed not. So, allow me to tell you a little more about the world the other you came from—”

“Please refer to him as Abdu El Yezdi,” Burton interrupted. “It will be less confusing.”

“Very well. In 1861, he killed the future Oxford, out of whose meddling these multiple histories were born. The following year, another man from the future tried to influence events. He was a Russian named Rasputin, who sent his spirit body back from 1914 in order to reshape the events that were leading to a war. El Yezdi killed him, too.”

“He appears to be rather violent,” Swinburne noted, with a glance at Burton.

“He’s had to be,” Brunel said. “And it’s taken its toll.”

Burton shifted uneasily in his chair. He lit a cheroot and raised it to his mouth with a trembling hand.

“In ’sixty-three,” Brunel continued, “El Yezdi himself became what you might call a chrononaut. He was thrown into the future, into 1918, where a world war had decimated the British Empire, which was making its last stand in a city called—”

“Tabora,” Burton croaked. “I witnessed its destruction last night.”

Brunel chimed, “How?”

“In a vision, forced upon me by an entity that calls itself Perdurabo.”

“Ah. Aleister Crowley.”

“Who?”

“In the war that threatens, there will be three great powers, all mediums of startling potency. In Germany, a man named Friedrich Nietzsche; in Russia, the aforementioned Rasputin; and for the British Empire, Aleister Crowley, who calls himself Perdurabo. He is a traitor and a madman. He has come among us to undo all the good work Abdu El Yezdi has done.”

“The manipulation of history,” Swinburne said. “To avoid the war?”

“Yes. After witnessing the conflict in 1918, El Yezdi attempted to repair the damage that Oxford had done to the mechanism of time. He traveled back through history to 1840, to the scene of Victoria’s assassination. When Oxford arrived from 2202, El Yezdi killed him—again. As it turned out, he also found himself responsible for Queen Victoria’s death.”

“The killing shot came from the rifle,” Burton whispered, remembering Trounce’s observation that the bullet had hit the monarch in the back of the head.

Brunel’s brass face turned so that he appeared to be looking straight at the explorer. “You will quickly learn to appreciate, Sir Richard, that where time is concerned, paradoxes proliferate and are impossibly baffling to any mind—with the exception, perhaps, of Charles Babbage’s. El Yezdi’s multiple murder of Oxford is far from being the most difficult of them to comprehend. The oddest is that, because El Yezdi prevented Oxford from being thrown back to 1837, three years of history suddenly vanished.”

“The Great Amnesia,” Burton said. “The Mad Marquess must have written about his encounter with Oxford at the precise moment history changed. His diary entry is an anomaly.”

“Oxford being thrown into ’thirty-seven, then not being thrown in ’thirty-seven, caused yet another branch to split from the original history—it is the one we inhabit—and El Yezdi was trapped in it. He’d already lived forty-two years in his own time, he spent four years in the future, and now he was back in 1840, aged forty-six, with his nineteen-year-old counterpart already there.”

“Me,” Burton said. “I always put it down to the effects of fever, but I think I felt his presence.”

“There is a resonance between versions of anything that possesses a multiple existence,” Brunel said. He rapped the side of his metal head. “The diamonds in which my consciousness resides, for example, are present many times over. Their resonation accentuates—even bestows—mediumistic abilities. It is how El Yezdi contacted Countess Sabina and through her began to shape a British Empire that would never go to war against Germany.”

The engineer said to Burton, “You have, quite literally, made history.”

Burton muttered, “And Perdurabo—Crowley—wants to destroy it.”

“He doesn’t believe the war can be avoided, so intends to ignite it earlier, before Germany can prepare. Once the conflict is won, he’ll make himself ruler.”

“Of Germany?” Swinburne asked.

“No, Mr. Swinburne, of the world. He has to be stopped.”

Burton suddenly jumped to his feet. “Do you have a map of London, Mr. Brunel?”

The electric man nodded and looked at Gooch, who crossed to a cabinet and returned with a rolled map. He unfurled it on Brunel’s desk, weighting the corners with a book, inkpot, spanner, and magnifying glass.

Everyone gathered around it.

Burton looked at the grandfather clock. It was eleven. He tapped a finger on the map. “Green Park. In exactly twenty-four hours, it will host a gathering of dignitaries from Britain and the Germanic states. The Central German Confederation will be formalised and our Alliance with it signed. Undoubtedly, Perdurabo will strike at the ceremony.”

“He’ll never get past the security,” Brunel said.

“He might intend to overpower the police and King’s Guard by force of numbers.”

“Has he an army?” Krishnamurthy asked.

“He has the Cauldron. Aleister Crowley currently exists only as parasitical willpower—a nosferatu. His victims become un-dead and are proliferating throughout the East End. He has power over them, and is using them to whip up fear and anti-German sentiment in the local population.”

A gruff voice came from the doorway. “Willpower, you say?”

They turned. Nurse Nightingale was guiding Abdu El Yezdi’s bath chair in through the door.

“My associate, the French occultist Eliphas Levi, calls it volonté,” Burton said.

His older self grunted an acknowledgment. “If Crowley is here only in such a form, we can be certain that his plans involve more than just a strike against the fledgling German Empire.”

“You refer to his need for a body?”

“I do. He is obsessed with the idea that medical and scientific intervention might hasten a man toward a state of godhood. He will attempt to achieve that.”

“A Supreme Man,” Burton muttered.

“Or as Nietzsche will have it, an Übermensch.”

“Artificially constructed?”

“I imagine so. I understand Galton escaped from Bedlam. Whatever he may have been in the original history, I’ve already seen him demonstrate just how thin is the line between genius and insanity. I have no doubt he’s been recruited by Crowley to create a physical structure in which our enemy’s volonté can be permanently housed.”

Burton nodded. “He also has Darwin and a talented surgeon named Joseph Lister, though they’re almost certainly being held against their will. And—” He hesitated.