‘It’s a raven,’ Ben said. ‘And I think I’ve seen it before.’ It was the symbol he’d seen carved in the central porch at Notre Dame Cathedral in Paris.

But why had Rheinfeld altered the design from the blade?

‘Does any of this mean anything to you?’ he asked Anna.

She shrugged. ‘Not really. Who knows what was in his mind?’

‘Can I have a look?’ Roberta asked. Ben passed the notebook to her. ‘God, it’s gross,’ she said, turning the pages with revulsion.

Ben’s heart was sinking again. ‘Did you learn anything at all from Rheinfeld?’ he asked Anna, hoping he might be able to salvage at least something of value.

‘I wish I could say yes,’ she replied. ‘When Dr Legrand first mentioned this strange, intriguing character to me I thought he might help to inspire me for my new book. I was suffering from writer’s block. I still am,’ she added unhappily. ‘But as I got to know him I felt so sorry for him. My visits were more for his comfort than for my own inspiration. I can’t say I learned anything from him. All I have is this notebook. Oh, and there is one other thing…’

‘What?’ Ben asked.

Anna blushed. ‘I did something a little…what’s the word…naughty. On my last visit to the Institut I smuggled in with me the little gadget I use for dictating my book ideas. I recorded my conversation with Klaus.’

‘Could I hear that?’

‘I don’t think it could be of any use,’ Anna said. ‘But you’re welcome to listen to it.’ She reached behind her and picked up a miniature digital recorder from a sideboard. She set it down in the middle of the table and pressed PLAY. Through the tinny speaker they could hear Rheinfeld’s low, muttering voice.

It put a chill down Roberta’s spine.

‘Did he always speak in German?’ asked Ben.

‘Only when he was repeating these numbers,’ Anna said.

Ben listened intently. Rheinfeld’s mumbling tone started low, mantra-like. ‘N-sechs; E-vier; I-sechs-und-zwanzig…’ As he went on his voice rose higher, beginning to sound frenzied: ‘A-elf; E-funfzehn…N-sechs; E-vier…‘and the sequence repeated itself again as Ben scribbled it down in his pad. They heard Anna softly saying ‘Klaus, calm down.’

Rheinfeld paused for a moment, and then his voice started again: ‘Igne Natura Renovatur Integra-Igne Natura Renovatur Integra-Igne Natura Renovatur Integra…’ He chanted the phrase over and over, faster and louder until his voice rose into a scream that distorted the speaker. The recording ended with a flurry of other voices.

Anna turned the machine off with a sad look. She shook her head. ‘They had to sedate him at that point. He was strangely agitated that day. Nothing seemed to calm him. It was just before he killed himself.’

‘That was creepy,’ said Roberta. ‘What was that Latin phrase?’

Ben had already found it in the notebook. He was looking at a sketch of a cauldron, in which some mysterious liquid was bubbling. A bearded alchemist in a smock stood watching over it. The Latin words IGNE NATURA RENOVATUR INTEGRA were printed on the side of the cauldron. ‘My Latin’s rusty,’ he said. ‘Something about fire…nature…’

‘By fire nature is renewed whole,’ Anna translated for him. An old alchemical saying, relating to the processes they used to transform base matter. He was fixated on that phrase, and when he repeated it he would count his fingers, like this.’ She imitated Rheinfeld’s twitchy, urgent gestures. ‘I have no idea why he did that.’

Roberta leaned across to see the picture in the notebook. Her hair brushed over Ben’s hand as she moved up close. She pointed to the image. Beneath the cauldron, the alchemist had lit a raging fire. Under the flames was the label ANBO, printed clearly in capitals. ‘Anbo- what language is that?’ she asked.

‘None that I know,’ Anna said.

‘So the notebook and this recording are all you have?’ Ben asked her.

‘Yes,’ she sighed. ‘That is all.’

Then it was a waste of time coming here, he thought bitterly. That was my last chance.

Anna was gazing thoughtfully at the rubbing of the dagger blade. An idea was forming in her mind. She couldn’t be sure, but…

The phone rang. ‘Excuse me,’ she said, and went to answer it.

‘So what do you think, Ben?’ Roberta said quietly.

‘I don’t think this is leading anywhere.’

They could hear Anna on the phone in the next room, talking in a low voice. She sounded a little flustered. ‘Edouard, I asked you not to call me any more…No, you can’t come here tonight. I have guests…no, not tomorrow night either.’

‘Me neither,’ Roberta said. ‘Shit.’ She sighed and got up from her chair, started pacing aimlessly across the room. Then something caught her eye.

Anna finished her call and returned to join them. ‘I’m sorry about that,’ she said.

‘Problems?’ Ben said.

Anna shook her head and smiled. ‘Nothing import ant.’

‘Anna, what’s this?’ Roberta said. She was examining a magnificent medieval text hanging in a glass frame on the wall near the fireplace. The cracked, browned parchment depicted an early map of the Languedoc, scattered with old towns and castles. Around the edges of the map, blocks of old Latin and medieval French text had been highly coloured and ornamented by a skilled calligrapher. ‘If this is an original scroll,’ she said, ‘it must be worth a packet.’

Anna laughed. ‘The American man who gave it to me thought it was priceless, too. Until he found out that the thirteenth-century Cathar script he’d paid twenty thousand dollars for was a fake.’

A fake?’

‘It’s no older than this house,’ Anna said with a chuckle. ‘About eighteen-nineties. He was so pissed off- is that the right expression?-that he gave it to me for nothing. He should have known. As you say, a genuine item in that condition would have been worth a small fortune.’

Roberta smiled. ‘We Yanks are suckers for anything more than three hundred years old.’ She moved away from the framed scroll and looked across at the tall, wide bookcase, running her eyes along the hundreds of books in Anna’s collection. There was so much here-history, archaeology, architecture, art, science. ‘Some of this stuff is so interesting,’ she murmured. ‘One day when I get time…’ She remembered she had a little book of Post-it notes in her bag, still out in the car. ‘Excuse me for a moment, will you? I want to write down a few of these titles.’ She trotted out of the room.

Anna moved close to Ben. ‘Come, I’d like to show you something,’ she said. He stood up, and she took his arm. Her hand was warm on his skin.

‘What do you want to show me?’ he said.

She smiled. ‘This way.’

The two of them walked out of the french window and down the long garden. At the bottom, a rocky path led up to the open countryside and after they had scrambled up a short slope Ben found himself looking out at a magnificent sunset panorama. He could see for miles across the mountains of the Languedoc, and above it all the sky was a cathedral-rich canvas of shimmering golds, reds and blues.

Anna pointed across the valley and showed him two distant castle ruins, serrated black outlines perched miles apart against the sky on high mountain peaks. ‘Cathar strongholds,’ she said, shielding her eyes against the falling sun. ‘Destroyed by the Albigensian crusade in the thirteenth century. The Cathars and their ancestors built castles, churches, monasteries, all across the Languedoc. They were all crushed by the Pope’s army.’ She paused. ‘I’ll tell you something, Ben. Some specialist historians have believed that these places have a deeper significance.’

He shook his head. ‘What kind of deeper significance?’

She smiled. ‘Nobody knows for sure. It was said that somewhere in the Languedoc there lies an ancient secret. That the relative positions of Cathar sites give the clue to finding it, and that whoever could solve the puzzle would discover great wisdom and power.’ Her dark hair was blowing in the gentle evening breeze. She looked beautiful. ‘Ben,’ she said tentatively. ‘You haven’t told me the whole truth. I think you’re looking for something. Am I right? Something secret.’