'Was it suicide?'

'How would I know? We'd separated by then.'

'But what do you think?'

Umber took a deep swallow of beer and stared at Sharp. 'Same as you.'

Sharp cleared his throat. 'According to my notes, I considered the possibility that you'd made the Griffin story up to explain your presence at Avebury.'

'And did you consider why I'd have wanted to be there?'

'Of course.'

'With what result?'

'I never figured it out.'

'That's because there was nothing to figure out.'

'It seems not.'

'Is that definite, then? You no longer think I might have been lying?'

'I'll go one better. I don't think you're lying now either. I just can't decide whether that's good news or bad.'

'What the hell does that mean?'

'It means you're wrong about Junius, Mr Umber. Somebody does give a damn.'

Umber grimaced in bewilderment. Perhaps he had drunk too much. Perhaps Sharp had. What in God's name was the man driving at?

'I had a letter a few weeks ago, basically telling me I cocked up the Avebury inquiry and should do something about it. Anonymous, naturally.'

'Did you think I sent it? Is that why you came all this way to see me?'

'Yes.'

'Well, you've had a wasted journey, then, haven't you?'

'I don't see it that way. You have to understand. You were the obvious suspect.'

'Why?'

'Because of the source of the letter.'

'You just said you didn't know who it was from.'

'I said it was anonymous. Maybe I should have said… pseudonymous. That's the really strange thing, you see. The letter… was from Junius.'

21. January

SIR, It is the misfortune of your life that you should never have been acquainted with the truth with respect to the Marlborough murderers.

It is not, however, too late to correct the error. I am unable to" correct it. It is time for those who have no view to private advantage, it is time for such men to interpose.

You have already much to answer for. The subject comes home to us all.

JUNIUS.

David Umber had read the letter several times and he was still unable to offer an intelligent response. Someone had cut various words and/or phrases out of an edition of the Junius letters and stuck them onto a sheet of paper to form this strangest of messages. It was a photocopy, of course. The letters themselves need not have been mutilated. But that was a small point. The overriding issue was: why?

'Aren't you going to say something?' Sharp prompted.

They were in the blandly decorated bar of Sharp's no-frills hotel near Charles Square. Umber had gone there in a mood of some scepticism, expecting to see something spectacularly un-Junian. But what Sharp had brought down from his room-safe was in fact eerily authentic.

'For God's sake, man, tell me what you make of it.'

'I don't know,' Umber said at last. 'I really don't know.'

'Are those Junius's words on the page or aren't they?'

'The words? Oh yes. I recognize some of the phrases. The start's from his famous letter to the King. The rest? I couldn't say exactly which letters they come from, but it's all Junius. The use of the long S confirms it as eighteenth-century type. The splitting up of the word "acquainted" is obviously an original line break. And the date's authentic too. Junius's first letter was dated the twenty-first of January, 1769. These must be extracts from one of the early collected editions.'

'Like the one Griffin was offering to show you?'

'Like it, yes. But -'

'It's tied up with that, isn't it?'

'How can it be?'

'Your guess is as good as mine. Or better. You are the Junius expert.'

'Was. A long time ago.'

'That still makes you one of the few people who could have put this letter together. I'll bet you've got a first-edition Junius tucked away somewhere.'

'Not so, actually.' It was true, thanks only to the flood, a detail Umber decided not to mention. 'Besides, I thought you accepted that I didn't put it together.'

'I do.' Sharp sounded as if he almost resented his own exclusion of Umber as a suspect.

'How was it addressed to you?'

'See for yourself.' Sharp slid the envelope across the table.

It was white A5, bearing a first-class stamp with a smudged postmark and what looked like a computer-generated address label. George Sharp, 12 Bilston Court, Nunswood Road, Buxton, Derbyshire SK17 6AQ. The word-processed characters held no clue. The clues, such as they were, had all been in the letter.

'London postmark,' said Sharp. 'Date barely legible. But probably the twenty-first of January. I received it on the twenty-second.'

'I was here at the time,' said Umber.

'That wouldn't clear you in my eyes.'

'Derbyshire, Mr Sharp. What took you there?'

'A return to my roots. And you can call me George, since we're in this together.'

Umber could not decide which was more ominous: the invitation to use Sharp's Christian name – or the hint of an alliance between them. He tried to ignore the point. 'My guess would be that whoever sent this chose Junius as the source in order to throw suspicion onto me.'

'If you're right, that means they know everything there is to know about the Avebury case. Your reason for being there didn't exactly make the newspaper front pages.'

'The implication is that they know the whole truth of it, surely.'

'Maybe. But the other implication is that I can find out what the truth is. If I set my mind to it. "It is not too late to correct the error." Notice he says "the Marlborough murderers".'

'I can't imagine Junius ever mentioned Avebury. But he would have mentioned the Duke of Marlborough. The town's only a few miles from Avebury, so-'

'That's not what I mean. Murderers plural. It rams the point home, doesn't it? It rules out Radd's confession.'

'We've already ruled that out, haven't we?'

Sharp sipped his whisky and offered no reply. But the deep furrows in his brow gave a kind of answer. The letter was a reproach as well as a challenge. And he was vulnerable to both.

'What do you mean to do about this?'

Still Sharp said nothing.

'George?'

Now, at last, there was a response. Sharp set down his tumbler with a clunk on the table. 'Exactly what it dares me to do.'

'"Correct the error"?'

'Dig out the truth. If it's there to be dug.'

'What can you hope to learn now that you failed to learn twenty-three years ago?'

'I'm not a policeman any more. I don't have to go by the book.'

'Have you reported receiving this letter?'

'Of course not. Wiltshire CID wouldn't want to know. And they'd try to spike my guns. The only advantage I have is that nobody will be expecting me to go down this road again.'

'Other than… what shall we call your correspondent?… Junius?'

'It's what he calls himself.'

'Or what she calls herself.'

'I suppose it could be a woman.' Sharp ground his teeth. "'I am unable to correct the error." "It is time for men to interpose." I see what you mean.'

'You're jumping to conclusions, George. The mid-eighteenth century's a tad early for gender equality. Junius – the real Junius – wouldn't have envisaged women interposing in anything. All I'm saying is that you don't know who you're dealing with.'

'Except that he or she is an expert on the Junius letters.'

'Not so very expert, actually.'

'What do you mean?'

'Well, I said Junius's first letter was dated the twenty-first of January 1769, and that's true – as far as the collected edition is concerned. But his first letter to the Public Advertiser appeared in November 1768. For some reason, he decided not to include it in the collected edition. Of course, that makes an original copy hard to come by, but the correct date could be concocted by…' Umber broke off and grabbed the letter. A door had opened in his mind. The writer could reasonably have hoped that Sharp would bring this letter to him. It could therefore be a message to both of them. Indeed, the sentiments were in many ways more applicable to him than to Sharp. 'The misfortune of your life.' Yes, what had happened at Avebury on 27 July 1981 was that all right. And the subject came home to him. Only too well. 'Bloody hell.'