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.'

III

'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.