At the end of the hall was a dark-­wood-­and-­glass revolving door, to its left an equally dark concierge desk.

The door was turning, slowing to a stop.

Someone had just passed through it.

“Major Koehler, sir?”

Koehler heard the call as he hit the first compartment of the revolving door, pushing hard, fighting its inbuilt resistance with gritted teeth and a barging shoulder.

The sentry on the steps flinched as Koehler erupted through, leaping down the four stone steps to the street, then sliding slightly to an ungraceful stop in the snow.

He was just in time to see the back end of a long, low black saloon car drift away around the far corner. Koehler grabbed his pockets, searching for his car keys, then remembered he’d left them in his coat in the apartment.

He felt impotent on the pavement in the falling snow. He looked at the sentry, who was now standing at attention, doing his best to ignore the panting SS major in front of him.

“That car?”

“Yes, sir?”

“Who was in it?”

The sentry turned his head to look toward where the car had gone.

“A man, sir, he looked like a civilian, in a suit.”

“How long where they here?”

The soldier shrugged. “He arrived not long after you, sir, had a smoke, and went into the—­”

The door behind the sentry started to turn again, slower this time. Koehler looked and saw through the glass that the concierge, an old Englishman whose name he could never remember, was leaning against the bar coming toward him.

Koehler stepped up to the door and gave it a shove with his good hand, speeding up the old man, who barely managed to get out of the compartment without getting his heels clipped.

The concierge held out an envelope. “I was calling you, Major. A gentleman left this, sir,” he said in English to Koehler, who stepped forward and snatched the envelope out of his hand.

It felt empty and had no name on it. Koehler ripped it open and noticed that its gum felt damp.

He looked back to the corner where the car had disappeared, then opened the flimsy piece of airmail paper inside, which read “MAYFAIR 6266.”

He looked at the other side, then back at the front.

“Did the man say anything to you when he gave you this?”

“No, sir.”

“Was he English?”

“I don’t know, sir.”

“How do you not know? He must have spoken to you; there is no name on the envelope.”

The old man wrinkled his nose and looked worried at the question, trying to think of the right answer to give.

“He just walked in, sir. He said ‘Major Koehler,’ gave me the envelope, then walked out. I couldn’t say where he was from, sir.”

Koehler looked back to the corner of the road, then ran a hand across his mouth before looking at the note again.

“Should I call for the officer of the watch, sir?” the sentry asked nervously.

“No,” Koehler replied, crossing the street and looking up at his apartment.

The snow was falling hard again and he blinked as flakes dodged and danced in front of his eyes. Some landed on his face. He wiped his cheek, then looked down at the pavement, where he saw the half-­hidden cigarette butt the man had dropped.

He bent to pick it up; it was smoked low to the end. Across the street the sentry and concierge watched him. Koehler stared back. The concierge looked away and ran a nervous hand across his waistcoat.

Koehler looked down at the snow again; he squinted, then flicked a finger across where he had found the cigarette butt.

There was a bullet.

He picked it up; it looked like a 9mm round.

Shiny, new, unfired.

Koehler stood up, squeezing the round tight in his hand. He looked up to his window, imagining how he would have looked staring down moments ago.

He shook his head, angry all over again that he had stood to the side. He walked back across the street, then stopped on the steps.

“Have you seen my wife today?”

“Yes, sir. She wanted a cab for one o’clock this afternoon, sir,” replied the concierge, still rubbing his stomach.

“Where was she going?”

“She didn’t say, I—­”

“She hasn’t been back?”

“Not that I’m aware, sir.”

Koehler checked his watch again.

He looked back across the road, as if expecting the ghost of the man he’d seen earlier to still be watching him.

“Thank you.” Koehler pushed against the revolving door.

“I can call the officer of the watch, sir; he won’t mind.”

Koehler didn’t reply; he was already back in the building.

THE APARTMENT SMELLED of cat shit. Koehler closed the door and crossed to the window, followed by a still-­complaining Schwarz.

Koehler pushed the window open wider, checking the street outside again.

The breeze blew the net back into his face and he swiped it away like a cobweb.

Everything was back to normal. No silent watchers, no smoking men.

Just bored sentries and snow.

Koehler took the note out of his pocket and went to the telephone next to the settee. He sat down, but before he could reach for the phone Schwarz plopped into his lap, head butting his hand while pawing his stomach. Koehler reached for the phone with one hand while stroking the cat with the other.

The phone rang four times before it was picked up.

“Hello?” a voice answered in English.

“Who is this?” asked Koehler, also in English.

“Major Koehler?”

“Who is this?”

Schwarz nuzzled his chin, so he pushed the cat down, twisting his head as he did so, struggling to hold the receiver against his ear.

“We have your wife and daughter.” The voice switched to German.

“What?”

“We have your wife and daughter. They are safe as long as you do exactly what we say. Do you understand?”

Koehler sat forward, squeezing Schwarz down tightly into his lap.

“Who is this?”

“You are to leave your apartment and drive to the corner of Bayswater Road and Queensway. There is a public telephone there. Enter the call box. There will be an envelope for you. Bring nobody; tell nobody. If you break these rules your family dies.”

The phone went dead.

Koehler looked at the receiver. He leaned back an inch and then realized Schwarz was digging his claws into his leg.