Inside, a few steps led down into a room full of damp darkness and cobwebs – and stacks of beige and grey Marlboro cigarette cartons, and a dozen garden gnomes. The gnomes leered in the sudden light; one of them was frozen in a fishing position. With grinning scarlet lips.

‘OK?’ said David, trying to quell his nerves. Now he could almost sense Miguel – nearing. Hunting them down. Blood finding blood.

‘OK,’ the others replied, as one.

They stepped inside the low chamber; the bar owner looked at them for a final second, shrugged as if they were obviously mad, then shut the tiny door.

Darkness enshrouded them. Apart from their one feeble torchbeam. David flashed it down the chamber, which went on, and on. A long passage into the chilly blackness.

‘Let’s go.’

They knew they had two kilometres to walk: the distance to Zbiroh. They began in silence. The sound of their footsteps slipping in the mud was the only noise they made. No one spoke.

Their hurried pace at last brought them to another door. An iron door. It was shut.

David slumped to the side. He could feel clammy mud on his back. He didn’t care.

‘Christ.’

Angus swore. Simon shook his head. David had his head weighed in his hands.

Another door. Just another door. That would stop them? He remembered all the doors he had been through these last weeks: the Cagot doors, the door in Navvarenx church, the door to the Holocaust museum, José’s door in the Cagot house, all the many doors. And now another door, defeating them. Just one last door, one door too far.

Amy stepped forward, she turned the handle to the door. It opened.

48

As one they passed through the doorway into a dark, brick-walled room, with a concrete floor.

David spun the torch, left to right. It was a large space; wooden chests were piled in severely neat stacks on each side.

Angus walked across and directed David’s torchbeam downwards, at one of the wooden chests. It had a motif burned into the surface: a large black Nazi swastika, clutched in the talons of an imperial eagle. And beneath it was an inscription, in Gothic lettering.

Die Fischer Experimente.

The lid of the first wooden case was easily prised off with Simon’s pocket knife. Amy found a paraffin lamp, with a wick, sitting at the back of the chamber. They flicked a lighter and turned the knob: the wick sent a good light across the shadowy chamber.

And then, for an intense and concentrated hour, they sat in a circle – and deciphered the documents, by torchlight and lanternlight. With Amy interpreting the German, and Angus’s knowledge of biochemistry and genetics, and Simon’s appreciation of the politics and history, they were a tensely effective team.

As they speedily pieced together the last elements of the story, Simon wrote it down, once again, sometimes squinting close to see the documents proffered to his gaze. Every so often, Angus would exclaim, or swear – ‘Fuck, so that’s why, so that’s what he found.’

Then Angus dropped the last document, and looked Simon’s way.

‘You’re the writer. Finish the story.’

Simon looked nonplussed for a moment, struck by the horror of it all, their discoveries, and their predicament. Then he said, quietly, ‘OK. So this is it. The last chapter.’

‘Go on.’

‘The first amazing discovery Fischer made was this: human speciation was happening. In Europe. Even as he watched. And it was the Cagots who were evolving.

‘As a result of their linguistic, cultural and social isolation, the Cagots had become a new kind of human. A new species. They were still able to breed, with difficulty, with their close relatives, Homo sapiens – but they were genetically drifting away. Fischer guessed that in a few generations the last Cagots would die out, thanks to these breeding problems. Their speciation from normal humans would be a failure.

‘Fischer relayed this information to Hitler, who was delighted. Here at last was proof that Nazism was just Applied Biology, as they had always boasted. Man truly differed from man. Indeed the racial differences within mankind were greater than even Hitler had speculated. Speciation was happening in Europe. It had happened to the Cagots…’

David glanced around, trying to contain his emotions. He wanted not to think of his own dark secrets, concealed in the vaults of his soul. Dooming him. Burying him under the concrete of his shame.

Then Simon turned a page.

‘Through 1941, correspondence between the Führer and his favourite scientist became ever more enthusiastic. Money poured into the camp to accelerate Fischer’s experiments. Hitler wanted proof that Germans were superior within the emerging hierarchy of races.

‘But then Fischer made a discovery at Gurs which was even more profound – and complicated. He predicted that the Cagot process would be repeated; he told Hitler that another species would soon splinter off from Homo sapiens, as the Cagots had done.’

Amy interrupted:

‘The Jews.’

‘As we see in the documents.’ Simon gestured at one of the open boxes. ‘Because of their religiously imposed self-segregation, their strictures against outbreeding – which enforced genetic isolation from the wider family of man – the Ashkenazi Jew was gradually becoming a new subspecies, maybe a new species, with a unique genotype. And all this Fischer told Hitler in a letter. This letter.’ He brandished the document, then returned to his notes.

‘Indeed Fischer told Hitler that, paradoxically, Nazi isolation of the Jews was only going to increase the chance and speed of this speciation. When he handed over the information, Fischer knew that Hitler would be excited by proof of Jewish Otherness. The problem was, as Fischer reluctantly told Hitler, the Jews were becoming, in some respects, a superior species. Certainly in terms of intelligence. Superior even to the Germans.’

He flipped a page. ‘How, ah, had this happened? Over centuries, Talmudic tenets and customs had emphasized the fame and renown of the scholar. For a Jewish girl in medieval Europe it was much more desirable to marry a brilliant rabbi than a successful merchant or a wealthy goldsmith.’

‘So the brainy, rather than the brawny, had more kids.’

Simon nodded at Amy.

‘The genetic evolution of the Jews was biased towards ever higher intelligence. Pogroms against Jews merely increased this effect. In times of great adversity and persecution only the most highly educated and adaptable Jews survived: the less bright Jews died off.’

He coughed, with a flicker of emotion. Then went on:

‘The…result of these centuries of upward pressure on Jewish intelligence, and the simultaneous genetic isolation in ghettos and shtetls, meant that Jews were speedily evolving into a more intelligent kind of human. There were downsides: Jews were and are uniquely prone to certain genetic ailments, like…how do you pronounce this…Tay-Sachs disease?’

Angus nodded. Simon returned to his text:

‘But the Jews were brighter. The syndromes might even have been the genetic price they had to pay for their cognitive gifts.

‘This remarkable discovery, when relayed by Eugen Fischer to the Führer in Berlin, chimed with the darkest fears in Hitler’s mind. Prior to this revelation, the Nazi leader had entertained other ambitious plans for Europe’s Jewry – sending them all to Madagascar, or using them as gifted slave labour in some far-off Russian province. But with the Fischer data in his hand, Hitler realized he had little choice. He had to strike now, while he controlled Europe, before those clever and very different Jews became truly dominant and different – and enslaved Germany in turn.

‘So in 1942 Hitler gave the go ahead for the Final Solution: the extermination of all European Jews, despite the huge cost and the possible crippling of the German war effort. Hitler had to end this menace to Aryan racial supremacy once and for all.