The few in this vast hive below who could put his face and a name to an act were all career criminals, who mattered less than nothing. Criminals could be bought or disposed of; as for Mr Holmes, well, it was all in the works now.

His current situation reminded him of a Vaudeville act he’d once gone to see at the urging of, oddly enough, Churchill. On the stage, a dapper gent juggled an increasing number of ever more disparate objects-a cricket ball, a roast leg of goose, a lit candle, a yelping puppy. The key element of the act had been the insouciance, even boredom, with which the fellow had caught each additional oddity thrown his way, incorporating it casually into his motions. The whole was intended to be madly humorous, as indeed the low-brow audience found it, but he thought it more effective as a paradigm: One’s raw material matters less than one’s confidence.

Take the telegram from the primitive reaches of the British Isles. Brothers had been-predictably-shocked at his failure to achieve the immortality of Divine Transformation up in Orkney, yet he overlooked the real question: How could a man, armed with knife, gun, and heavy narcotics, not only fail at murder, but manage to get himself wounded as well?

Another ill-matched object to keep up in the air.

Ah, well. That was what one got from depending on elaborate plots with many moving parts. It had all been far too beautiful, too gorgeously complex and inexorable-until an artist had inexplicably failed to die, and dropped a spanner into the clockworks.

Still, it wasn’t a total loss. Parts of the machine were still turning nicely, and since they were dependent only on his own actions, they would continue to run. From here on out, he would abandon the complex, and keep things simple, and brutal.

The clock across the way told him it was time for sleep: He had a seven o’clock appointment, a full day of meetings, and a trip to St Albans to arrange. He drained his glass and went to bed, where he slept without dreams.

The grey-haired man in the dusty stockings stood in his London prison and studied the equation on the wall. The odd dreaminess of his imprisonment made it an effort to direct his mind to the formula and what it represented; still, it was what Buddhists called a koan, a focal point for the mind, a conundrum with a puzzle at its core.

a ÷ (b+c+d)

Ironic, to use schoolboy maths-beaten into him when Victoria still wore colour-to develop a theorem for the most complex and dangerous political manoeuvring of his career.

As ironic as the entire situation being based on a simple truth of governmental bookkeeping: A department immune to budget cuts is the most powerful department in the government.

a ÷ (b+c+d)

The a in the formula was his position in His Majesty’s Government, a job his brother Sherlock had once whimsically described as “auditing the books in some of the Government departments.” It was an apt description, in both the meanings of auditor: one who examines the accounts, and one who listens.

He had listened to a lot of secrets, in his career.

In his first draughts of this formula, a had represented himself, but he had revised that and replaced the person with the position; b was the age of the present incumbent. Not that he felt old, but he had to admit, the looking-glass in his bathroom startled him at times. c stood for the Labour Government, new, fragile, and perceived by many as a vile Bolshevik threat. And d, of course, was his own heart attack last December, the subsequent convalescence, and the lingering sense of vulnerability and impermanence.

He pinched the nail between his fingers, and paused.

His e was to be he, himself, the sum of nearly half a century of auditing the books of the empire. But on which side did that fifth element go: debit, or credit?

Once, that old man in the glass had been strong and flexible in mind and body. Now, he lived in an age where youth was all, where flightiness was virtue, where a man of a mere seventy years was made to feel outdated. Where Intelligence had become a Feudal stronghold, with peasants clamouring at the gates.

Once, he’d lived in a world where one could tell a man’s profession and history by a glance at his hands and the turn of his collar, but now every other man spent his days in an anonymous office, and even shopkeepers wore bespoke suits.

Perhaps his time was past…

But, no; e was himself and the rest was mere doubt: He added an upright to the horizontal line he’d scratched, and the equation read:

a ÷ (b+c+d) + e

e, after all, was Mycroft Holmes. Lock him in a dank attic, withhold his meals, force him to use his neck-tie as a belt and a slip of metal for a pencil, starve him of information and agents and human tools, ultimately there was no doubt: He would walk away. Sooner or later, his mind would cut through solid wall, build a ladder out of information, weave wings out of words and clues and perceived motions.

He found that he was sitting on the floor; the angle of light through the translucent overhead window had shifted. Odd. When had that happened? For a moment, a brief moment, he entertained the possibility that lack of adequate sustenance was making him light-headed.

But surely the past eight months of denying the body’s surprisingly strong urges, shedding 4 stone 10 in the process, would have hardened him to thin rations?

No, he thought. It was merely the disorientation that comes with a prolonged lack of stimulation. Still, he could not help wishing that he had been gifted with his younger brother’s knack of using hunger to stoke the mental processes. Under present circumstances, Sherlock’s mental processes would be fired to a white-hot pitch that would melt the walls.

Personally, Mycroft found a growling stomach a distraction.

The business end of a gun is remarkably distracting. It dominates the world. So it wasn’t until the weapon fell away that I looked past it to see the familiar scarred features of my pilot, who swore and reached for my arm. “There you are! I’ve known some troublesome girls in my time, but sweetheart, you take the-oh, hey there, honey, come on in,” he added in a very different voice, and the hand at his side shifted to hide the gun completely. He peeled back the door to encourage us to enter, standing almost behind it so as not to frighten the child at my side.

“I didn’t see you there, little Miss,” he said. His voice was soft with easy friendship, and it occurred to me that he might have had a family, back in America before the War and the ’plane crash that left his face and hand shiny with scar tissue. “Do come in, it’s chilly out there and Mrs Ross would be happy to set some breakfast in front of you. That’s right, in you come, and pay no attention to the big ugly man who met you with a growl.”

Estelle glued herself to my side. When the door was shut, she peered around me at Javitz. I looked down and said, “Estelle, this is the man with the aeroplane. He didn’t mean to frighten you.”

“What’s on your face?” she asked him.

He gave no indication of the distress it must have caused, this first reaction from any new acquaintance. “I got burnt, a long time ago. Looks funny but it doesn’t hurt.”

“Did it hurt then?”

“Er, yes. It did.”

“I’m sorry.”

After a minute, he tore his gaze away from her to look at me. “Where have you been?”

“Probably best you don’t know, just yet. Why the, er, armament?”

“Someone tried to jigger with the machine last night. I happened to be outside and heard them, so I stood guard to make sure they didn’t get another chance. The lad took over at daybreak. I was about to set out and look for you.”