But the gang had come to an area without any mobile phone reception. Why had they done that? Was it possibly their first mistake? Forrester felt his hopes rising. You needed luck in this job. This might be his stroke of luck.

The interview was finished. The teapot was empty. Outside, the lid of grey clouds had partially lifted. Slants of sunshine shone down on the wet fields. The policemen lifted their trousers from the mud as they walked with the farmer down to the Balladoole Road.

‘Just through here,’ said Spelding. ‘This is where I saw them.’

They all gazed across the rucked and muddy field, bordered by the small country road. A doleful cow was staring at Boijer. Beyond the cow was a long curve of grey sand, and then the frigid grey sea, lit by the occasional dazzle of sunshine.

Forrester indicated the lane. ‘Where does that go?’

‘To the sea. That’s all.’

Forrester climbed the last gate; followed by Boijer and the rest, who showed rather less alacrity. He stood exactly where the car had parked. It was an odd place to stop if you were headed for the bay. It was half a mile back from the shoreline. So why did they park here? Why not drive the last half mile? Did they fancy a walk? Clearly not. So they must have been looking for something else.

Forrester climbed back on to the nearest gate. He was nine feet in the air now. He looked all around him. Just fields and stone walls and sandy meadows. And the unhappy sea. The only point of interest was the nearest field. Which, from Forrester’s vantage, showed some shallow bumps, and stray rocks. He got down from the gate and turned to Harnaby, who was panting from the walk. ‘What are they?’ asked Forrester. ‘Those little bumps?’

‘Well…’ Harnaby was smiling unsurely. ‘I was going to mention it. Not many people know about it but that’s the Balladoole burial site. Vikings. Eleventh century. It was dug up in the 1940s. They found brooches and the like. And…something else too…’

‘What?’

‘They also found a body.’

Harnaby elaborated. He told them about the great excavation during the war when scientists from the mainland had unearthed an entire Viking ship, interred with jewellery and swords. And the body of a Viking warrior. ‘And there was also evidence of human sacrifice. At the warrior’s feet, the archaeologists found the body of a teenage girl. She was probably a sacrificial victim.’

‘How do they know?’

‘Because she was buried without any grave goods. And she was garrotted. Vikings were quite partial to a bit of sacrifice. They would kill slavegirls to honour fallen men.’

Forrester felt a reflexive quickening. He looked at Boijer. He looked at the distant grey waves. He returned his gaze to Boijer. ‘Ritual sacrifice,’ he said at last. ‘Yes. Ritual human sacrifice. Boijer! That’s it!’

Boijer seemed puzzled. Forrester explained:

‘Think about it. A man buried alive with his head in the soil. A man with his head shaved-and his tongue cut out. Ritual carvings on both bodies…’

‘And now Balladoole,’ said Harnaby.

Forrester gave a brisk assent. Jumping over a second gate, he crossed to the bumps and rocks in the field. His shoes were ruined by mud but he didn’t care. He could hear the sounding waves from the beach; taste the tang of oceanic salt. Beneath him Vikings had interred a young woman, a woman who had been ritually slain. And these men, these murderers, had communed here: before committing their own ritualized execution: just a few hours later.

The clockwork was whirring. The machinery was engaged. Forrester inhaled the muggy moist air. Smirrs of grey cloud were racing in, from the roiled and choppy Irish Sea.

The Land Rover sped down the dirt track away from Sogmatar towards the main Sanliurfa road, twenty klicks alongside the ancient arroyo. Christine was staring ahead, concentrating on the road, her hand tight on the gearstick. They drove in silence.

Rob hadn’t told her what he thought he had discovered about the numbers. He wanted to prove it to himself first. And for that he needed a book, and maybe a computer.

By the time they arrived back in the city the sun was an hour from sunset and Sanliurfa was notably busy. As soon as they reached the centre they went straight to Christine’s flat, flung dusty jackets onto the wickerwork chair and flopped onto the sofa. And then Christine said, quite unexpectedly, and apropos of nothing, ‘Do you think I should fly home?’

‘What? Why?’

‘The dig is over. My salary stops in a month. I could fly home now.’

‘Without finding out what happened to Franz?’

‘Yes.’ She stared out of the window. ‘He is…dead. Shouldn’t I just accept it?’

The sun was dying outside. The muezzin were calling across the ancient city of Urfa. Rob got up, went to the window; creaked it open, and gazed out. The cucumber man was cycling down the pavement shouting his wares. Veiled women were in a group outside the Honda shop talking into mobile phones through their concealing black chadors. They looked like shades, like ghosts. The mourning brides of death.

He went back to the sofa and gazed at Christine. ’I don’t think you should go. Not yet.’

‘Why not?’

‘I think I know what the numbers mean.’

Her face was motionless. ‘Show me.’

‘Do you have a Bible? An English one?’

‘On that shelf.’

Rob paced to the shelf and checked the spines: art, poetry, politics, archaeology, history. More archaeology. There. He took down a big old black Bible. The proper authorized version.

At the same time Christine took Breitner’s notebook from the desk.

‘All right,’ said Rob. ‘I hope I’m right. I think I’m right. But here goes. Read out the numbers in the notebook. And tell me what they’re next to on the page.’

‘OK, here’s…twenty-eight. Next to a compass sign, for east.’

‘No, say it like the two numbers are separate. Two eight.’

Christine stared at Rob, perplexed. Maybe even amused. ‘OK. Two eight. By an arrow pointing east.’

Rob opened the Bible to Genesis, thumbed through the thin, almost translucent pages and found the right page. He ran his finger down the dense columns of text.

‘Chapter two, verse eight. 2:8 Genesis. “And the LORD God planted a garden eastward in Eden; and there he put the man whom he had formed”.’ Rob waited.

Christine was staring at the Bible. After a while she murmured, ‘Eastward in Eden?’

‘Read another one.’

Christine scanned the notebook. ‘Two nine. Next to the tree.’

Rob went to the same page in the Bible and recited, ‘Book of Genesis. Chapter two, verse nine. 2:9 “And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil”.’

Christine said in a low voice, ‘Two one zero. Two ten. By the river squiggly thing.’

‘The line that turns into four rivers?’

‘Yes.’

Rob looked down at the Bible. ‘Chapter two, verse ten. “And a river went out of Eden to water the garden; and from thence it was parted, and became into four heads”.’

‘My God,’ said Christine. ‘You’re right!’

‘Let’s try one more, to make sure. A different one, one of the big numbers.’

Christine went back to the notebook. ‘OK. Here are some bigger numbers, at the end. Eleven thirty-one?’

Rob fanned through the pages and recited, feeling like a vicar in his pulpit, ‘Genesis. Chapter eleven, verse thirty-one. “And Terah took Abraham his son, and Lot the son of Haran his son’s son, and Sara his daughter in law, his son Abraham’s wife; and they went forth with them from Ur of the Chaldees, to go into the land of Canaan; and they came unto Haran, and dwelt there”.’

‘ Haran?’

‘ Haran.’ Rob paused, sitting down next to Christine. ‘Let’s try one more, one more of the others, one of the numbers next to a drawing.’