‘This extraordinary indulgence of a scientist seen as a founder and mentor of Nazi racial politics was by no means unique. Many of Fischer’s colleagues at Gurs and elsewhere also escaped punishment, or endured at most a few weeks of “deNazification” in prison. For example, Professor Doctor Fritz Lenz, the head of eugenics at Berlin Dahlem, and a coauthor of key works on Nazi racial theory, returned to work immediately after the war, and was offered the chair in human heredity at the University of Gottingen.’

These last assertions were so bizarre Simon read the whole passage twice. Then he read it again. Then he checked it on another website, which repeated the statement word for word.

Word for word? Simon began to wonder if the remarkable claim was simply a lie, perpetuated by the lazy scholastic standards of the internet.

He got up, opened the door, and walked into the living room. Conor was playing on the carpet with his toys, transfixed by the adventures of Derek the Diesel Engine.

There – the bookshelves. High up on the highest shelf, gathering dust these ten years, was his father’s old Encyclopedia Britannica. Simon pulled down the volume, paged quickly to Lenz, Fritz.

It was true. This beast, this horrible man, this expounder of eugenics, this friend of Mengele, this thinker behind Nazism, had calmly returned to work in 1946. He hadn’t even gone to jail. The Allies didn’t even put him in jail.

Why were all these doctors just…let off?

He tousled his son’s blond hair, then returned to his study and shut the door. Again. He was excited. The mystery was coming alive, but it was coiled upon itself, like a snake, a cobra, hissing. Concealing what lay within.

His afternoon was nearly done. He went over the facts by writing down the words in an email to himself – one of his favourite ways of resolving a puzzle. Like an artist turning his own drawing upside down, to see it afresh, to spot the flaws, assess the quality.

Simon sat back from the computer, and sighed. His thoughts were incoherent, they were drivel, they were utter nonsense. Money, Nazis, Cagots, possible collaboration, so what? He had no overarching explanation for the murders: which now seemed almost random.

He felt his momentary excitement subside. He was almost back to where he started. He needed to speak to David and Amy. He needed to speak to David. Where were they? What was happening down there in southern France?

He remembered Tomasky’s sister. What she had said. A monastery in France.

In France? A monastery called Tourette.

Hunched forward, Simon typed.

The screen returned his answer at once.

The monastery of La Tourette.

Built between 1953-1960, at the instigation of Reverend Father Couturier of the Dominican Order of Lyon. Architect Charles Edouard Jeanneret-Gris (known as Le Corbusier).

Simon paused.

The Dominican Order?

He remembered what Professor Winyard had told him. The Dominicans. The Dogs of God. The burners of witches. The hammer of witches. The Malleus Malleficarum.

Now his pulse quickened, dramatically. This monastery was apparently near Lyon. Near Lyon?

David Martinez had told Simon about the map that had been owned by David’s father and handed on by David’s grandfather. On that map, as Simon recalled, was one curious outlier, one hand-drawn blue star that was way beyond the Basque region, way outside the purlieus of the Cagots. Wasn’t that near Lyon? Or was it Marseilles? It was Lyon, wasn’t it?

The mystery coiled and hissed.

He read on.

Le Corbusier, the websites told him, was the greatest architect of the last century. He was also renowned for his purity, his cleanliness of vision: utilizing the precept form follows function. Everything he did was deliberate. He was also known as an atheist, ‘therefore the commission to design this post-war monastery of La Tourette came as a surprise’.

But many things about this monastery were, it seemed, a surprise. Where the money came from – in impoverished post-war France. Why the Dominicans suddenly decided to construct a large priory when so many old and war-damaged buildings were in need of repair. Most of all, why the building had such a strange design.

As one book phrased it: Le Corb’s idea was that living in this building, ‘La Tourette’, should be, in itself, a penance. The daunting nature of the structure, the difficulty of living within it, should be part of the austerities of the monastic life.

These austerities, it seemed, were more than theoretical. The building was ‘largely finished’ in 1953. By 1955 ‘half the initial community of monks had mental disorders’. These included nervous breakdowns and major depressions, and they occurred precisely ‘because the building was so oppressive’. The jarring spaces and the brutalism of the design apparently tipped the denizens over the edge.

Another factor, one critic claimed, in the ‘outright unpleasantness’ of the building, was the acoustics. At night ‘every single sound in the building was amplified’. Every breath, every whisper, every snore. This was apparently ‘a function of the concrete fabric and the inherently echoic spaces’: in other words, the hostile nature of the building was a deliberate feature, designed to disorientate.

There was one more website. It was an architecture blog. A simple, humble blog, written by an architecture student from Brisbane. Who had apparently stayed at La Tourette a few summers back, after years of research on Le Corbusier.

The essay began with a short autobiographical note. And then launched into a blistering attack on the architect.

The basic allegation of the student was that Le Corbusier was a Nazi. During the war years, it seemed, Le Corbusier was very close to Pétain, the leader of the puppet French fascist regime of Vichy. Le Corbusier was also, the author alleged, a big fan of Hitler. The essay quoted one ‘notorious’ remark, when the architect said the Führer was ‘marvellous’.

The blog attempted a counterbalancing argument. Admitting that Le Corbusier was not alone, that many architects had fascist or Marxist sympathies: because architects are utopians. Architects want to change society. It doesn’t necessarily make them Nazis or communists or killers…

The blogpost drew to a close with another barb. It made the claim that Le Corbusier’s famous building in Marseilles, the Unite d’Habitation, was the most popular place to commit suicide in the South of France. And yet, the essay said, the monastery of La Tourette was even more oppressive – the only reason it didn’t see so many suicides was because visitors tended to flee after a few days. The monks had to stay, and suffered terribly, and yet their religious vocations prevented self murder.

And then the essayist asked the obvious question: Why? Why did the Dominicans mysteriously commission a man like Le Corbusier to build a mysterious structure like this?

Simon shut down the computer to listen to the silence in his study, and the major chord of logic in his mind.

The essay blog might have finished on a query. But the answer was obvious, to Simon. Form follows function: that was Le Corbusier’s lifelong belief. The function of this building was maybe to shelter facts, maybe appalling facts. The building was a subtly authentic statement of that sinister function. Herein lies evil. Do not come near. Like the vivid and offputting colouration of a poisonous insect.

He recalled Professor Winyard’s exact words about those vital documents: the materials relating to the blood tests of the Cagots and the burning of the Basque witches. The documents suppressed and hidden by the Papacy.

‘They were kept at the Angelicum, the Dominican University in Rome. For centuries they were safe. But then after the war, after the Nazis, they were felt to be less safe, too provocative. There are rumours that they were spirited away, to somewhere more secure. But no one knows where.’