He began to feel defensive, shut in, a feeling he remembered from Vienna, when he had been the target of the 'anti-relativity clubs' and other anti-Semitic groups. 'How did you find all this out? Slept with half the faculty, did you?'

She smiled at him, naked, entirely composed. 'And I know what else you've been working on. Something even Godel doesn't know about. Something to do with relativity, and all this mushy stuff about internal time and the mind… Something that goes beyond mere theory. And I know you haven't been working alone. I'm talking about Rory O'Malley.'

'What do you know about Rory?'

'I have a feeling I know more about your Irish friend than you do.' She ran a languid finger up the length of his bare arm; he shivered, despite himself, and buttoned his shirt. 'Come on, Ben. Spill the beans. The rumour is-'

'Yes?'

'That you and your Irish boyfriend have built a time machine.'

He hesitated. 'It's not like Wells's fantasy, not at all. And we played with ideas – concepts – that's all. We went through some of the calculations-'

'Are you sure that's all?'

'Or course I'm sure! We haven't done anything. We decided we mustn't, in fact, because-'

'Rory O'Malley isn't terribly discreet. Surely you know that much about him. That's not what he's been saying.'

As the import of her words sank home, Ben's stomach clenched. Was it possible? But how, without his knowledge? Oh Rory, what have you done?

Julia saw his fear, and laughed at him. 'I think you'd better give Rory a call. We've a lot to talk about.'

'I studied physics,' Rory said slowly. 'I was a bright kid. I was fascinated by relativity. I bet there weren't so many other fifteen-year-old students in Dublin in the 1920s who owned a copy of Einstein's 1905 papers – still less who could read them in their original German.

'But I was drawn to history as well. Why was a man like Einstein singled out for his Jewishness? Why, come to that, had the Christian church – I was an Irish Catholic – always been in such dreadful conflict with the Jews? So I began to study history. Religion. Philosophy…' He spoke uncertainly, plucking at his fingers.

Rory was dark, darker even than Ben. He joked that the Irish strain had been polluted by swarthy Spaniards washed ashore from the wreckage of the Armada. There was a trace of scar tissue at Rory's neck, the relic of the Nationalist bullet that had nearly killed him in Spain. Rory was a stocky, bullish man, an Irishman who had made himself a place in America, and had embraced mortal danger in Spain. Yet he seemed intimidated sitting before Julia, who was dressed in her customary style, an almost mannish suit of jacket and trousers, with a shirt-like blouse and a loosely knotted neck-tie, her perfect face framed by cigarette smoke.

The three of them sat in Rory's apartment, here at the leafy heart of Princeton. The living room was small but bright, with long sash windows pulled open to admit the green air of an American spring day. They sat on battered, grimy furniture amid loose piles of books, volumes on physics and history, on the roots of Christianity and the philosophical implications of Einstein's relativity. It was a jumbled, disorganised, dusty room, but it reflected Rory O'Malley, Ben thought, as if it were a projection of his own mind.

It had taken a couple of weeks for Julia to set up this meeting. She hinted darkly that she had wanted some time to verify some aspects of Rory's 'account' for herself, and she had arrived today with a slim briefcase, presumably containing the fruits of that research. Ben found himself gazing at the briefcase with dread.

And he felt uncomfortable at how Rory was opening up his soul, and Ben's, to Julia's interrogation.

He said sharply, 'You don't have to talk to her if you don't want to, Rory. I mean, who is she?'

Rory looked at him bleakly. 'Don't you know?'

Julia just smiled.

'I'll tell you who she is,' Rory said. 'She's an officer in the fucking SS. That's who she is. She's done more than shake Hitler's hand.'

Ben stared at her, appalled.

Julia extracted a fresh cigarette from the silver box she carried. 'Oh, don't look so shocked, Benjamin. I apologise for keeping it from you. But you'd hardly have slept with me if you'd known, would you? Let's get on with it. You met in Spain, during the Civil War.'

Hesitantly, uncomfortable, Rory spoke.

When only twenty-two, Rory had moved to New York from his native Dublin, ostensibly to study. But, a strong-minded idealist, he had quickly made a name for himself as an outspoken columnist. Then he had gone to Spain to work on a book on the seven-centuries-long history of coexistence and conflict between Christianity and Islam in the peninsula.

'I was in Seville when it all kicked off. The Civil War. The city fell to Franco's Nationalists within days. The bloodshed was worse after the cities fell, as the Nationalists took reprisals. So I fled north, to the Republican areas.'

'And there he met you?' Julia asked Ben.

Ben said reluctantly, 'I had already seen enough of the fascists in Germany. I went out to fight in the International Brigades. I never went back to Austria after that. I got some help from the Americans in my brigade, and they eventually got me into the country, and a place here at Princeton to continue my studies.'

Julia said briskly, 'I've never been terribly impressed by the Spaniards. They had all that wealth, a global empire, gold from the Incas and the Aztecs. And they blew the lot on dynastic wars within a century of Columbus. As for their Civil War, what a pointless conflict that was!'

'Three hundred and fifty thousand died,' Rory said angrily. 'Many of them to German and Italian bombs and bullets.'

'New ways of fighting wars were rehearsed. An imperial nation was reduced to a testing ground for the weapons of superior powers. So much for Spain!'

Ben snapped, 'You're damn cold, Julia.'

Julia laughed. 'No. Just realistic. Were you lovers?'

They spoke at the same time. 'No,' said Rory, and, 'Only once,' said Ben, more wistfully.

'And it was in pillow talk in Spain, I suppose, that you began to dream of time machines.'

'It was a pooling of interests,' Ben said.

Rory said, 'Studying history, I had come to feel a vast dissatisfaction. It need not have been this way! All the suffering, all the blood spilled – especially that provoked by religions, by prophets of peace. I wondered if it need be so – I longed for it not to be so.' He glanced at Ben. 'Then there was Ben's idle talk of Godel, this eccentric mathematical genius who twisted Einstein's equations and imagined it might be possible to reach out, around what he called "closed timelike curves, to touch the past…'

'That and my dreams,' Ben said.

Julia eyed him. 'What dreams?'

'I have always had intense dreams. Often they are like memories of visits to scenes in the past – and the future. Once or twice-'

'Go on.'

Rory said, 'There was one dream, of the bullet which nearly killed me.' He touched his neck.

'You are precognitive,' Julia said to Ben.

'So John William Dunne might say. He might speak of my animus floating free in a multidimensional spacetime.'

'Is that what you believe?'

'No.' He sighed. 'I'm one of the most rational people you're likely to meet, Julia. I don't even believe in God. And yet others believe such powers of me. Isn't that an irony?'

'And so from all this,' Julia said, 'from hints of precognition, from Godel's speculation about travel into the past, you began to design a time machine.'

'Not a machine,' Rory said. 'Though we gave it a machine-like name.'

'The Loom.'

'Yes. But it's a method, really.'

'A method for touching the past. For changing it. Is that right? And after Spain you came to this institute, where you worked together on realising your "method. You went so far as to wangle time on a calculating engine in Massachusetts. And you, Rory, began to work out, if you could make a change to the history that you found so unsatisfactory, exactly what change should be made.'