“KP17, this is KHQ. KP17, answer please!” A woman’s urgent voice filled the car. March picked up the radio handset concealed under the dashboard.

This is KP17. Go ahead.”

“KP17, I have Sturmbannfuhrer Jaeger for you.”

He had arrived outside the gates to Buhler’s villa. Through the metalwork, March could see a yellow curve of drive and the towers, exactly as the sentry had described.

“You said trouble” boomed Jaeger, “and we’ve got it.”

“Now what?”

“I hadn’t been back here ten minutes when two of our esteemed colleagues from the Gestapo arrived. ‘In view of Party Comrade Buhler’s prominent position, blah blah blah, the case has been redesignated a security matter.’ ”

March thumped his hand against the steering wheel. “Shit!”

“ "All documents to be handed over to the Security Police forthwith, reports required from investigating officers on current status of inquiry, Kripo inquiry to be closed, effective immediately.

“When did this happen?”

“It’s happening now. They’re sitting in our office.”

“Did you tell them where I am?”

“Of course not. I just left them to it and said I’d try and find you. I’ve come straight to the control room.” Jaeger’s voice dropped. March could imagine him turning his back on the woman operator. “Listen, Zavi, I wouldn’t recommend any heroics. They mean serious business, believe me. The Gestapo will be swarming over Schwanenwerder any minute.”

March stared at the house. It was utterly still, deserted. Damn the Gestapo.

He made up his mind at that moment. He said: “I can’t hear you, Max. I’m sorry. The line is breaking up. I haven’t been able to understand anything you’ve said. Request you report radio fault. Out.” He switched off the receiver.

About fifty metres before the house, on the right side of the road, March had passed a gated track leading into the woods that covered the centre of the island. Now he put the Volkswagen into reverse gear, rapidly backed up to it, and parked. He trotted back to Buhler’s gates. He did not have much time.

They were locked. That was to be expected. The lock itself was a solid metal block a metre and a half off the ground. He wedged the toe of his boot into it and stepped up. There was a row of iron spikes, thirty centimetres apart, running along the top of the gate, just above his head. Gripping one in either hand, he hauled himself up until he was in a position to swing his left leg over. A hazardous business. For a moment he sat astride the gate, recovering his breath. Then he dropped down to the gravel driveway on the other side.

The house was large and of a curious design. It had three storeys capped by a steep roof of blue slate. To the left were the two stone towers the sentry had described. These were attached to the main body of the house, which had a balcony with a stone balustrade running the entire length of the first floor. The balcony was supported by pillars. Behind these, half-hidden in the shadows, was the main entrance. March started towards it. Beech trees and firs grew in untended profusion along the sides of the drive. The borders were neglected. Dead leaves, unswept since the winter, blew across the lawn.

He stepped between the pillars. The first surprise. The front door was unlocked.

March stood in the hall and looked round. There was an oak staircase to the right, two doors to the left, a gloomy passage straight ahead which he guessed led to the kitchen.

He tried the first door. Behind it was a panelled dining room. A long table and twelve high-backed carved chairs. Cold and musty from disuse.

The next door led to the drawing room. He continued his mental inventory. Rugs on a polished wooden floor. Heavy furniture upholstered in rich brocade. Tapestries on the wall — good ones, too, if March was any judge, which he wasn’t. By the window was a grand piano on which stood two large photographs. March tilted one towards the light, which shone weakly through the dusty leaded panes. The frame was heavy silver, with a swastika motif. The picture showed Buhler and his wife on their wedding day, coming down a flight of steps between an honour guard of SA men holding oak boughs over the happy couple. Buhler was also in SA uniform. His wife had flowers woven into her hair and was — to use a favourite expression of Max Jaeger — as ugly as a box of frogs. Neither was smiling.

March picked up the other photograph, and immediately felt his stomach lurch. There was Buhler again, slightly bowing this time, and shaking hands. The man who was the object of this obeisance had his face half-turned to the camera, as if distracted in mid-greeting by something behind the photographer’s shoulder. There was an inscription. March smeared his finger through the grime on the glass to decipher the crabbed writing. To Party Comrade Buhler,” it read. “From Adolf Hitler. 17 May 1945.”

Suddenly, March heard a noise. A sound like a door being kicked, followed by a whimper. He replaced the photograph and went back into the hall. The noise was coming from the end of the passage.

He drew his pistol and edged down the corridor. As he had suspected, it gave on to the kitchen. The noise came again. A cry of terror and a drumming of feet. There was a smell, too — of something filthy.

At the far end of the kitchen was a door. He reached out and grasped the handle and then, with a jerk, pulled the door open. Something huge leapt out of the darkness. A dog, muzzled, eyes wide in terror, went crashing across the floor, down the passage, into the hall and out through the open front door. The larder floor was stinking-thick with faeces and urine and food which the dog had pulled down from the shelves but been unable to eat.

After that, March would have liked to have stopped for a few minutes to steady himself. But he had no time. He put the Luger away and quickly examined the kitchen. A few greasy plates in the sink. On the table, a bottle of vodka, nearly empty, with a glass next to it. There was a door to a cellar, but it was locked; he decided not to break it down. He went upstairs. Bedrooms, bathrooms — everywhere had the same atmosphere of shabby luxury; of a grand lifestyle gone to seed. And everywhere, he noticed, there were paintings — landscapes, religious allegories, portraits — most of them thick with dust. The place had not been properly cleaned for months, maybe years.

The room which must have been Buhler’s study was on the top floor of one of the towers. Shelves of legal text books, case studies, decrees. A big desk with a swivel chair next to a window overlooking the back lawn of the house. A long sofa with blankets draped beside it, which appeared to have been regularly slept on. And more photographs. Buhler in his lawyer’s robes. Buhler in his SS uniform. Buhler with a group of Nazi big-wigs, one of whom March vaguely recognised as Hans Frank, in the front row of what might have been a concert. All the pictures seemed to be at least twenty years old.

March sat at the desk and looked out of the window. The lawn led down to the Havel’s edge. There was a small jetty with a cabin cruiser moored to it and, beyond that, a clear view of the lake, right across to the opposite shore. Far in the distance, the Kladow-Wannsee ferry chugged by.

He turned his attention to the desk itself. A blotter. A heavy brass inkstand. A telephone. He stretched his hand towards it.

It began to ring.

His hand hung motionless. One ring. Two. Three. The stillness of the house magnified the sound; the dusty air vibrated. Four. Five. He flexed his fingers over the receiver. Six. Seven. He picked it up.

“Buhler?” The voice of an old man more dead than alive; a whisper from another world. “Buhler? Speak to me. Who is that?”

March said:’A friend.”

Pause. Click.

Whoever it was had hung up. March replaced the receiver. Quickly, he began opening the desk drawers at random. A few pencils, some notepaper, a dictionary. He pulled the bottom drawers right out, one after the other, and put his hand into the space.