'This trip he's taking to Marlborough – wouldn't you be better off challenging his word after he's had his tete-a-tete with Jane?'

'Whose side are you on, Marilyn?'

'Whose do you think?'

'Not mine.'

'You could be wrong about that.'

'Could I?'

'Tell you what. I'll make you an offer. As a sign of my… intentions.'

'What kind of offer?'

'I stand a much better chance than you do of finding out for certain whether Oliver's had this man Wisby on some kind of long-term retainer – and, if so, why. As a matter of fact, I want to find out. In case I'm one of the subjects he's been enquiring into.'

'Surely not.' Umber could not resist playing Marilyn at her own game to some degree.

'Stranger things have happened.'

'And the offer?'

'I'll pass on everything I learn to you.'

'Why would you do that?'

'Because I know nothing about this, David. And Oliver isn't supposed to have any secrets from me. If he has, well, I might need an ally. Someone I can trust.'

'Think you can trust me?'

'Yes.' She smiled. 'Of course I do.'

'I'm not sure you can.'

'Well, maybe hope's a better word, then.'

'Ever heard of somebody called Griffin?'

'No.'

'Sure?'

'I think I am.' She gazed at him in silence for a moment, her eyes narrowing slightly. Then she said, 'Or is hope a better word again?'

Umber felt both encouraged and disturbed by his visit to Kingsley House. He sat in a coffee shop in Curzon Street, trying to sift the good from the bad in his mind. He had a lead, of sorts, and a spy in the enemy camp whose reliability was questionable to say the least. The Halls were pursuing different and conflicting strategies, for reasons Umber was a long way from understanding. He was entangled in both. And entanglement with Marilyn, tempting though it undeniably was, seemed certain to lead to disaster. He could not trust her. But he could not afford to ignore her. By rights, he should agree his next move with Sharp. But Sharp was still en route to Jersey, phoneless and infuriatingly out of touch. For the moment, Umber was on his own.

The British Library was open until eight o'clock on weekdays. The books Umber had ordered could wait a while. Sensing he would not be able to concentrate on them until he had explored at least one other avenue where Wisby was concerned, he headed for Green Park Tube station.

His destination was Southwark, where Wisby Investigations Ltd operated out of an address in Blackfriars Road. Umber had learned this much from Claire Wheatley's telephone directory. He had also learned the phone number, of course, and could have spared himself the risk of a wasted journey by calling ahead, but he wanted to see just what sort of an operation it was, so he decided to try his luck in person.

171A Blackfriars Road was a first-floor office above a shoe-repair business. 22IB Baker Street it was very far from. A young, yawning Asian woman was the sole occupant. She broke off from typing on a word processor that looked about twenty years old to tell him, 'They're all out,' without apparently feeling the need to explain who they were.

'I'm looking for Alan Wisby.'

'He's retired.'

'I don't think so.'

'Oh yes, he has. Since before I started here.'

'When was that?'

'Nearly a year now. Monica Wisby's in charge. She's out at the moment.'

'When will she be back?'

'I don't know. Could be soon. Could be… late. Do you want to leave a message?'

'For what it's worth, yeah.'

She grabbed a notepad and pen. 'What's your name?'

'Umber. David Umber. Monica's already -'

'You're David Umber?' She looked surprised.

'Yes.'

'Can you… prove it?'

Umber took out his wallet and placed his brand-new British Library reader's card on the desk. The young woman looked at the photograph on it, then up at him, then down at the photograph again. 'Satisfied?'

'Sorry. I had to be sure.'

'Any particular reason?'

'Monica said you might turn up, but I wasn't to hand it over or even mention we had it – unless you had some ID.'

'What are you talking about?'

'This letter.' She opened the desk drawer and took out a sealed buff envelope. 'It's for you.' She handed it over.

Umber stepped back to the doorway before opening the letter, unsure how to react to such a turn of

events.

His name had been printed on the envelope using an old-fashioned typewriter in need of a change of ribbon. There was one sheet of paper inside, so thin that some strikes of the keys had perforated it. It bore neither address nor date, but was signed at the bottom A.E. Wisby.

Dear Mr Umber

Monica apprised me of Sharp's visit to my old place of business. He gave her your name and mobile number for me to contact. I don't trust phones or policemen, so we'll keep this between ourselves if you don't mind. I'm willing to talk to you as long as you come alone. I'm on the Kennet and Avon at present, between Newbury and Kintbury. You'll recognize the boat's name when you see it. Don't leave it too long, or I'll have moved on.

Umber made it to Paddington in time to catch a crowded five o'clock commuter train bound for Bedwyn, stopping just about everywhere en route, including Newbury and Kintbury. From the guard he learned that Kintbury station was right next to the canal, which clinched his choice of destination. He somehow doubted Wisby would have moored in the centre of Newbury anyway.

The train reached Kintbury at 6.30. The sun had set by then, behind dark clouds rolling in from the west. A still, greying twilight filled the air. Umber lingered on the platform, watching the other passengers who had got off leave the station. The canal was separated from the railway line by the width of the small station car park. The village of Kintbury lay to the south, the lane into it crossing the canal over a humpback bridge. There was a pub on the other side of the bridge. One of the departing passengers was making straight for it. The others were clambering into their waiting cars.

The guard blew his whistle. The train rumbled off into the dusk. The level-crossing gates rose. The vehicles they had been holding back drove on. The car park emptied. Within a few minutes of the train's arrival, there was no-one left in sight. Umber was alone in the descending silence and gathering gloom. He headed for the towpath.

It was plainly foolish to set off on such a search in failing light. But the truth was that biding his time had simply not occurred to him until he was on the train. He doubted he would have found the patience to wait until morning in any event. Besides, Wisby was more or less certain to be aboard his boat come evening. To that extent, this was exactly the right time to go looking for him.

On the other hand, it had to be five or six miles to Newbury and it would be pitch black long before Umber got there. He was pinning his hopes on finding Wisby's boat within the first couple of miles. There were no boats moored ahead that he could see, but that was not far on account of the canal's winding route. He walked faster and faster, breaking occasionally into a jog as the sky darkened.

Wisby's choice of the Kennet and Avon Canal was not a matter of chance, of course. Umber was keenly aware of that. Marlborough lay no more than ten or twelve miles to the west, an easy bus-ride from Bedwyn, the canal's closest approach to the town. Wisby was in the area for a reason and was content to let Umber guess what that reason might be. He could hardly know about the towpath walk Umber had taken with Sally after the inquest all those years ago, but the memory of it was hovering close to Umber. Nor was it the only memory crowding in on him. He was a man fleeing the past as well as pursuing it.