As he approached Neuengamme, he felt the weak flutter of a dull and imprecise anxiety. For Fabel, this was a land laden with the past. This is where so much good and bad came together for him. It was an intimate thing. For Fabel, all kinds of history merged in this unlikely bump in the Elbe: personal, professional, national.

As all German children of his generation had had to, Fabel had taken on the burden of his nation’s history when he was about ten: a loss of innocence and a coming to terms. He had asked his father about the things he had heard. About Germany. About themselves. About the Jews. Fabel recalled the sorrow in his father’s eyes as he had struggled to frame for a ten-year-old boy the monumental monstrosity of what had been done in the name of Germany. It had been shortly after that that his father had made the long journey here. To this place with its pretty half-timbered houses and gentle landscape. To Neuengamme.

More than 55,000 prisoners had been worked to death here, in a camp improvised from a disused brick factory. The British had liberated it, as they had Bergen-Belsen, and with typical Anglo-Saxon efficiency and practicality had handed it back to the German people in 1948, suggesting it would make a good prison. And that’s what it had become. Until 1989, a Holocaust memorial and Vierlande Prison had shared the same site. Eventually, the Hamburg Senat saw the bizarre and bitter irony of continuing to confine human beings on the site of such atrocities in the name of the state, and the Vierlande facility was moved outside the former camp.

And now Fabel had come to Vierlande to face, for the first time in over a decade, a part of his personal history that he thought he had long since buried.

The prison officer led Fabel to Dorn’s study. It was a bright, airy room with large colourful posters of German historical landmarks on the wall: Lübeck city gates, Trier’s Porta Nigra, Cologne cathedral. The room was lined with bookshelves and Fabel felt it had more the look of a school library than that of Dorn’s old study at the Universität Hamburg. When Fabel entered, Dorn and a younger man were bent over a reference book. The younger man towered above Dorn and his T-shirt exposed heavily muscled and tattooed arms. His brutish appearance sat incongruously with the intense concentration he was applying to the text. Dorn looked up and saw Fabel, made an excuse to the scholarly thug, who left with the volume and his notebook under his arm.

‘Jan …’ Dorn extended his hand. ‘I’m glad you could come. Please, sit down.’

Time had flecked more white through the trimmed moustache and goatee, and had drawn more deeply around the eyes, but apart from that Mathias Dorn was pretty much as Fabel remembered him back when he had been Fabel’s European History tutor: a small, neat, compact man with porcelain-blue eyes and features that were a little too fine. Fabel took the frail hand.