‘How? I don’t get it!’ Amy was pale with anger; her white face framed by the yellow sands of the Naukluft, through the window. ‘Eloise? She is no madwoman. And she never said any of this?’

‘Well, she wouldn’t, would she?’ Angus spat out his sarcasm. ‘It’s the great wild shame of the Cagots, not something you mention to the neighbours – why don’t you pop round for a dinner, bring a fat friend -’

‘But what’s the science?’ David steered the car between two dead and spiky trees. ‘Cannibalism? How the hell does that…evolve?’

Angus frowned. ‘It’s because of the inbred isolated nature of the Cagots. Take their syndactyly, webbed toes and feet. This is typical of mountain peoples, with small gene pools. Syndactyly is associated with many chromosomal disorders. Some of them lead to psychoses, violence, strange sexual urges – who knows – you see?’

Any flashed a glance at David, then at Angus.

‘Miguel was highly…sexual.’

‘Excess libido, yep.’ Angus was actually smiling. ‘Hypersexuality, satyriasis. And the hypersomnia.’

‘He always fell asleep after sex.’

‘Typical man. What can you do.’ Angus gazed at nothing, then went on: ‘So, I suspect, Miguel has some obscure combination of Klein Levin and Hallervorden-Spatz syndromes, not unknown to the average Cagot. This syndrome will get worse over time. And one of the psychosexual symptoms can be anthrophagy. Cannibalism! I realized he had cannibalist urges when I saw him sniffing the smoke…last night.’

David checked the mirror: there was some obvious and shocking sadness in the Scotsman’s aggressive humour, his determined smile.

Amy said: ‘So that’s why the euphorbia worked.’

‘Exactly. After I watched him with poor Alfie, I knew he would want to sniff the smoke again, the smell of burning…human flesh. I realized he would do that when they started to toast you, David. Wouldn’t be able to resist.’

‘And euphorbia?’

‘Euphorbia virosa. Also known as Bushman’s poison. Eating the leaves will kill you quickly. The woodsmoke can kill over time and knock you out very quickly. My gamble was that Miguel would step forward and inhale, try and smell the delicious scent.’

David felt a profound queasiness, like vertigo:

‘But Angus. If Miguel hadn’t stepped forward and…inhaled…the euphorbia smoke would have killed me.’

‘Yes, well. I figured you wouldn’t mind dying quicker by poison rather than waiting to be chargrilled.’

The car was quiet. The old dirt track turned onto a proper road. Black and tarmacked and murderously straight: like a fine needle of jet pointing due south. The sun was azimuthal in the sky, the shapes of running ostriches spotted the far and desolate horizon. David thought of his frail grandfather, back at the hospice in the desert: desolada, desolada, desolada.

The sadness and shame of his grandfather; the terrible fate of his parents.

Amy spoke: ‘Where are we going?’

‘Rehoboth. City of the Bastards.’

‘Sorry?’

David checked in the mirror, Angus was still wearing that odd, cocky smile.

‘I’m going to see Alphonse’s mother, just for a minute. To tell her what happened. Alphonse was a Baster. A Bastard. His mother lives in Rehoboth and we need to get there soon because Miguel is not dead and his men will find a way out of the desert and they will come to the Sperrgebiet, they will come for Eloise -’

Amy interjected: ‘Why didn’t he believe you? When you told him Eloise was in the Forbidden Zone? Why did he continue to…do what he did? He had his answer.’

Angus scoffed.

‘You still don’t see? This man is driven by his shameful urges, his Cagot cannibalism. Probably he has kept a hold on it for years, but as the syndrome worsens the most primal and evil of his desires are surfacing -’

‘He bit the hand of the Cagot woman he killed in Gurs. Eloise’s grandmother. The cop called it “experimental” -’

‘There you are. In one. He’s yielding to these base desires, at last, as he goes finally mad. The syndrome tightens and grips. You can overtake this car – we need to keep moving.’

It was the first vehicle they had seen in an hour. David sped by, the car driver was a big, German-looking man. Who flashed his headlights as they passed: two blinks of silver in the shimmering heat.

Angus continued: ‘So you see, Miguel used our predicament as an excuse to…cook someone. He had his answer but his impulses were predominant. What he really wanted was human flesh. As much as possible. A chance to feed his worst urges. He couldn’t help himself.’

‘And now?’

‘He will be after Eloise. He still has a job to do, after all. Destroy the experiments and stop our tests and then kill Eloise, the last of the Cagots.’

A terrible thought struck David.

‘Angus…Is Eloise also mad?’

‘No. Not every Cagot suffers these syndromes. She’s fine. And plenty of Cagots are – or were – perfectly healthy. Especially at the beginning of their…isolation.’

‘But then?’

‘As the gene pool dried up, over centuries, the bad genetic stuff recrudesced, healthier Cagots became rarer, and so the poor mad Cagots were shunned with ever greater severity, as a pariah tribe, and so the vicious genetic circle tightened. They were forced to inbreed, due to lack of partners; perhaps they were reduced to incest. Thus creating more cannibals and cretins and web-toed rapists. We better get petrol.’

The fuel station was a sudden outpost of sophisticated business in the bleak empty desert. One minivan was decanting half a dozen nuns, black nuns with smiling black faces, laughing. A couple of motorbikers were sitting in the shade, pouring bottles of water over their sunburned foreheads.

Watered and refuelled, they bought nuts and wizened apples and sticks of biltong. Then they climbed back in. The endless black strip of the road unfurled through the wastes.

Angus was still talkative: it was as if he saw conversation as a way of avoiding any contemplation of what they had been through. David was happy to go along; he, likewise, didn’t want to consider what they had so recently endured.

‘So tell me. You two.’ Angus sank some water. ‘We need to know who betrayed us.’

‘Yes…’

‘I think it’s pretty obvious. Don’t you?’

David said: ‘No.’

Angus tutted.

‘You were obviously set up in Swakop. By that guy. Hans Petersen. He was waiting for you. Like you just bumped into him and he kindly drove you to see us? Och right. I had suspicions when you showed but I was a halfwit, got distracted, didn’t do anything about it. Didn’t think.’

David protested:

‘I don’t think he’d betray us – No -’

‘Fuck that, it was him. The elephant man. He is known in Namibia, hates Nazis, any hint of racial science. They probably told him we were doing the Fischer experiments, he agreed to help – do a set up – I should have guessed.’

‘We didn’t tell him why we were going.’

‘He knew already. They had someone in Swakop tell him, so he was ready to befriend you, so you would give away Eloise’s whereabouts, lucky for us I moved her -’ Another slug of water. ‘Anyfuckinghow, here we go. The City of the Bastards.’

They were driving into a largish town, ringed with fuel stations and metal bungalows. Telephone masts stood whitely on shallow dusty hills, the streets were wide and languid in the heat and blessed with German names: Bahnhofstrasse; Kaisersstrasse. Big dogs ran behind tall wire fences. Dark orange girls laughed outside a pink bungalow called Viljoen’s Pool Hall. David rolled down the window and stared at the shoppers stepping inside one supermarket, Spar.

The people were strikingly beautiful. Like Alphonse. Coffee-coloured skin, slanting eyes, extraordinarily elegant cheekbones.

‘So who are the Basters?’

Angus explained. ‘The crossbred descendants of strapping Dutch settlers and petite khoisan tribesmen: the famous Bushmen of the kalahari. The Dutch and the Bushmen intermarried in the eighteenth and nineteenth centuries. In the Cape Colony. Take a left here. This is where -’ His voice cracked for a second. ‘This is where Alphonse’s family live. I met him at Windhoek University. I needed an assistant. He was so beautiful, a beautiful bastard of Rehoboth.’