Then she kissed him and said, 'I should get to the airport. You'd better miss me.' He'd wanted to give her a lift to Heathrow but she said, 'Don't be silly, I'll jump on the Tube to Paddington and catch the Heathrow Express.' He didn't like her taking the Tube, he didn't like anyone taking the Tube any more. Fires and accidents and suicide bombers and police marksmen and nutters who could send you falling under a train with just a quick prod in the back -the Underground was a fertile place for disaster. He didn't use to think like that, he had a couple of wars and a lifetime of appalling events beneath his belt, but somewhere along the lonesome highway he passed the tipping point -more years behind him than in front of him -and had suddenly begun to fear the random horror of the world. The train crash was the ultimate confirmation.

'I'm sure it'll come to you soon,' the policewoman said. 'It's probably best for your recovery if you don't worry.'

'I used to be a policeman,' Jackson said. Every time he hit the dead end of the existential labyrinth he seemed to find it necessary to assert this. His identity might have been called into question but of this one fact he was sure.

It seemed unlikely that news of the train crash would reach Tessa in Washington, something pretty big had to happen in Europe before it percolated through the American consciousness. At worst, she would have tried to text him and wondered why he hadn't replied, but she wouldn't immediately jump to the conclusion that he had got himselfinto trouble, unlike his first wife,Josie. His first wife, how strange that sounded, especially as when she was married to him she used to think it was amusing to introduce herself that way, Hello, I'm Jackson's first wife.

Of course, Tessa had had no idea that he was on that train, had no idea that he was out of London because he'd never mentioned it to her, never said, 'Actually, once you're on your way to the airport I'm going north to see my son.' And the reason he hadn't said that was because he'd never told her about Nathan. So quite a lot of sins of omission going on, and in such a new marriage, when there should have been no secrets. And, of course, even if she had known he was on the King's Cross train, it wouldn't have mattered because he wasn't. You're going the wrong way. His head hurt. Too much thinking makes Jackson a dull boy.

They had hardly been apart since they met. She went to work every day, of course, but they often met up at the British Museum during her lunch hour. Sometimes after they had eaten they wandered around the building, Tessa talking to him about some of the exhibits. She was a curator, 'Assyrian mainly,' she said when they first met. 'Well, it's all Greek to me,' Jackson joked weakly. The Assyrian came down like a wolf on the Jold. Even her guided tours of the Assyrian bit didn't enlighten him much. He was sure there was a better word than 'bit'. 'Department', was that the word? 'The Assyrian Department' that didn't sound right, it sounded like a bureaucratic niche in the underworld.

Despite some carefully worded explanations from Tessa he still wasn't entirely sure that he understood the where/what/when of Assyria. He thought it might have something to do with Babylon. By the waters oj Babylon we sat down and there we wept when we remembered Zion. Not a Boney M song but Psalm 137. We remembered Zion, we remembered our songs, Jar we could not sing here. The song of the exile. Wasn't everyone an exile? In their hearts? Was he being mawkish?

Probably.

New information was hard to retain, because of the amount of useless old information littering his brain. It was strange that the one thing that he seemed to remember from school was poetry, probably the subject he had paid least attention to at the time. Dirty British coaster with a salt-caked smoke stack.

He kept a photograph of her in his wallet, alongside one of Marlee, but the wallet was still missing. He could home in on a feature, the long-lashed brown eyes, the nice straightness of her nose, a neat ear, but nothing fitted together into a proper portrait. She was Picasso rather than Vermeer. He should have studied Tessa more, taken more photographs, but she was chronically camera-shy, as soon as she spotted a lens she would mask her face with her hand and, laughing, say, 'No, don't! I look terrible.' She never looked terrible, even first thing in the morning when she had just woken up she seemed flawless. It was difficult to believe that out of all the men on the planet she had chosen him. ('Very difficult,' Josie agreed.)

The objective, more world-weary part of Jackson knew that he was foxed by love, that he was still in the heady spring days of the relationship when everything in the garden was rosy and blooming. My love is like a blood-red rose. No, not blood. Red. Red, red rose. 'Your salad days,' Julia said. 'Green in judgement.' 'And what does this paragon amongst women see in you exactly?' Josie asked. 'Apart from the money, of course.'

'How old is she?' Julia asked, a histrionic look of horror on her face.

'Thirty-four,' Jackson said reasonably.

'That's cradle-snatching, Jackson,' Josie said.

'Bollocks,' Jackson said.

'You know that being in love is a form of madness, don't you?' Amelia said. (,Then it must be aJolie adeux,' Tessa laughed when he told her.) Amelia had (dreadful to recall) once been in love with Jackson. He must phone Julia, find out how Amelia's operation had gone. Was she dead? Julia would be inconsolable. There was a phone by the side of his bed but he needed a credit card to operate it and the credit card was in his wallet. If he had Andrew Decker's wallet, did Andrew Decker have his? Andrew Decker's wallet was almost bare, the old driving licence, a ten-pound note. Travelling light. Was he in the hospital somewhere?

The photograph in his wallet was the only one he had ofTessa, taken on Jackson's camera by one of their impromptu witnesses after their hasty wedding and even on that auspicious occasion she had tried to turn away from the camera. Now he didn't even have that. No wallet, no BlackBerry, no money, no clothes. Born naked, reborn naked.

'We hardly know each other,' she said when he proposed.

'Well, that's what marriage is for,' Jackson said, although his experience of marriage tended to indicate the opposite -the longer he and Josie were married the less they seemed to understand each other.

Tessa didn't change her name to his, she had never 'seen herself' as Mrs Brodie, she said. Josie hadn't changed her name either when she married him. The last 'Mrs Brodie' that Jackson knew was his mother. Jackson's sister, an old-fashioned girl in every sense, used to tell him that she couldn't wait to be married and ditch her maiden name and 'become Mrs Somebody Else'. That's what she was -a maiden, a virgin, 'saving herself for Mr Right'. There were always boys after her but she still hadn't found anyone steady when she was raped and murdered. She had a bottom drawer, a little chest in her room that was neatly layered with tea towels and embroidered traycloths and a stainless-steel cutlery set that she was adding to, one item a month. All for the life to come that never came. All these things seemed so far away now, not just Niamh herself but all the girls who saved embroidered tray-cloths and stainless-steel cutlery sets. Where were they now?

Most people carried a couple ofphoto albums with them through their lives but he had never come across a single photograph in Tessa's Covent Garden flat. Her parents were dead, killed in a car crash, but there was no sign they had ever existed. There was nothing from her childhood, no souvenirs of the past at all. 'I live in the past in my job,' she said. 'I like to keep my life in the present. And Ruskin says that every increased possession loads us with weariness, and he's right.'