He listened in silence while, at his request, she recounted the sequence of events between the arrival of Sir George at Kingly Street and her discovery of Clarissa's body. She had handed over the collection of messages and they were spread out on the desk before him. From time to time, as her quiet voice rose and fell, he shifted them about as if searching for some meaningful pattern. She was glad that she wasn't wired up to a lie machine. Surely the needle must have leapt as she came to those moments when, although she told no direct untruth, she carefully omitted the facts which she had decided not to tell; the death of Tolly's child, Clarissa's disclosure in the Devil's Kettle, Roma's unsuccessful appeal to her cousin for money. She didn't try to justify these suppressions by pretending that they wouldn't be of interest to him. She was too tired now to make up her mind about the morality of her decision. She only knew that, even when recalling Clarissa's battered face, there were things that she couldn't bring herself to tell.

He made her go over her story again and again, particularly pressing her about the locking of the bedroom doors. Was she absolutely certain that she had heard Clarissa turn her key? How could she be so sure that she had, in fact, locked her own door? Sometimes she wondered whether he were deliberately trying to confuse her as a counsel for the defence might, pretending to be obtuse, pretending that he hadn't quite understood. She was increasingly aware of her own tiredness, of his strong hand lying in the pool of light from the desk lamp, the ruddy hair gleaming on the back of his fingers, of the soft rustle as Sergeant Buckley turned the page. She must have been speaking for well over an hour before he finished the long interrogation and both their voices fell silent. Then he said suddenly, as if rousing himself from boredom:

'So you call yourself a detective, Miss Gray?' 'I don't call myself anything. I own and run a detective agency.'

'That's a nice distinction. But we haven't time to go into it now. You tell me that Sir George Ralston employed you as a detective. That's why you were here when his wife died. Suppose you tell me what you've detected so far.'

'I was employed to look after his wife. I let her be killed.'

'Now, let's get this straight. Are you telling me that you stood by and let someone kill her?'

'No.'

'Or killed her yourself?' 'No.'

'Or encouraged, or helped or paid anyone else to kill her?' 'No.'

'Then stop feeling sorry for yourself. Presumably you didn't think she was in any real danger. Nor did her husband. Nor did the Metropolitan Police apparently.'

Cordelia said:

'I thought that they might have had a reason for scepticism.' His eyes were suddenly sharp. 'You did?'

'I wondered whether Miss Lisle sent one of the notes herself, the one typed on her husband's typewriter. He was in America at the time so he couldn't have posted it to her himself.'

'And why should she do that?'

'To try to exonerate Sir George. I think she was afraid that the police might suspect him. Don't they usually think of the husband first? She wanted to make sure that he was in the clear, perhaps because she didn't want the police to waste their time on him, perhaps because she genuinely knew that he wasn't guilty. I think the Metropolitan Police might have suspected that she sent the message herself.'

Grogan said:

'They did more than suspect it. They tested the saliva on the flap of the envelope. It belonged to a secretor with the same blood group as Miss Lisle, and that group is rare. They asked her to type an innocuous note for them, a message which had some of the same letters and in the same order as the quotation. On that evidence»they suggested, tactfully, that she might have sent the note. She denied it. But you could hardly expect them to take the death threats very seriously after that.'

So she had been right. Clarissa had sent that one message. But she might be wrong about the reason. It had, after all, been clumsily done, and had it really exonerated Sir George? But it had ensured that the police took no further interest in what they must have seen as the time-wasting mischief of an attention-seeking and probably neurotic woman. And that would have suited the real culprit very well. Had anyone suggested to Clarissa that she should send that one note herself? And had it been the only one for which she had been responsible? Could the whole sequence of quotations be an elaborate conspiracy between herself and one other person? But Cordelia rejected that theory almost as soon as it came into her mind. Of one thing she was sure: Clarissa had dreaded the arrival of the messages. No actress could have simulated that fear. She had been convinced that she would die. And she had died.

Cordelia was aware that the two men were looking at her intently. She had been sitting silently, hands curved in her lap, eyes lowered, occupied with thought. She waited for them to break the silence and when the Chief Inspector spoke she thought she could detect a different note in his voice which could have been respect.

'Did you deduce anything else about these notes?'

'I thought that they might have been sent by two different people, apart from Miss Lisle, I mean. I wasn't shown the first half dozen which she received. I thought it possible that they might have been different from the later communications. And most of the ones I saw, the ones I've handed over to you, can be found in The Penguin Dictionary of Quotations. I think that whoever typed them had that book in front of him and typed from the text.'

'On different machines?'

'That wouldn't be difficult. They aren't new machines and the makes are different. There are numerous shops in London and the suburbs which sell new and reconditioned typewriters and which put out a machine or two for people to try. It would be almost impossible to trace a machine if one went from shop to shop and typed a few lines in each.'

'And who do you suggest did?'

'I don't know.'

'And what about the original anonymous correspondent, the one you might say who had the bright idea in the first place?' 'I don't know that either.'

That was as far as she was willing to go. She had told them enough, perhaps too much. If they wanted motives, let them grub around for themselves. And there was one motive for the poison pen that she would never divulge. If Ivo Whittingham had kept silent about Tolly's tragedy, then so would she.

And then Grogan was speaking again, leaning over the desk towards her so that the powerful body, the strong coarse voice surged towards her, palpable as a force.

'Let's get one thing straight, shall we? Miss Lisle was battered to death. You know what happened to her. You saw the body. Now, she may not have been a good or likeable woman. That has nothing to do with it. She had as much right to live her life to the last natural moment as you or I or any creature under the Queen's peace.'

'Of course. I don't see why that needs saying.'

Why did her own voice sound so small, almost peevish?

'You'd be surprised what needs saying in a murder investigation. It's the most powerful mutual protection society in the world, the trade union of the living. It's the living you'll be thinking about, wanting to protect, yourself most of all of course. My job is to think of her.'

'You can't bring her back.'

The words, torn out of her, fell between them in all their sad banality.

'No, but I can stop someone else from going the same way. No one is more dangerous than a successful murderer. I'm boring you with platitudes because I want you to get one thing straight. You may be too bright for your own good, Miss Gray. You're not here to solve this crime. That's my job. You're not here to protect the living. Leave that to their lawyers. You're not even here to protect the dead. They're beyond needing your condescension. On doit des regards aux vivants; on ne doit aux morts que la verité. You're an educated young woman. You know what that means.'