‘You don’t think that Parker himself might be the man we’re after?’ I suggested.

‘It looks very like it. He was obviously listening at the door when you came out. Then Miss Ackroyd came across him later bent on entering the study. Say he tried again when she was safely out of the way. He stabbed Ackroyd, locked the door on the inside, opened the window, and got out that way, and went round to a side door which he had previously left open. How’s that?’

‘There’s only one thing against it,’ I said slowly. ‘If Ackroyd went on reading that letter as soon as I left, as he intended to do, I don’t see him continuing to sit on here and turn things over in his mind for another hour. he’d have had Parker in at once, accused him then and there, and there would have been a fine old uproar. remember, Ackroyd was a man of choleric temper.’

‘Mightn’t have had time to go on with the letter just then,’ suggested the inspector. ‘We know someone was with him at half-past nine. If that visitor turned up as soon as you left, and after he went, Miss Ackroyd came in to say goodnight – well, he wouldn’t be able to go on with the letter until close upon ten o’clock.’

‘And the telephone call?’

‘Parker sent that all right – perhaps before he thought of the locked door and open window. Then he changed his mind – or got in a panic – and decided to deny all knowledge of it. That was it, depend upon it.’

‘Ye – es,’ I said rather doubtfully.

‘Anyway, we can find out the truth about the telephone call from the exchange. If it was put through from here, I don’t see how anyone else but Parker could have sent it. depend upon it, he’s our man. But keep it dark – we don’t want to alarm him just yet, till we’ve got all the evidence. I’ll see to it he doesn’t give us the slip. To all appearances we’ll be concentrating on your mysterious stranger.’

He rose from where he had been sitting astride the chair belonging to the desk, and crossed over to the still form in the armchair.

‘The weapon ought to give us a clue,’ he remarked, looking up. ‘It’s something quite unique – a curio, I should think, by the look of it.’

He bent down, surveying the handle attentively, and I heard him give a grunt of satisfaction. Then, very gingerly, he pressed his hands down below the hilt and drew the blade out from the wound. Still carrying it so as not to touch the handle, he placed it in a wide china mug which adorned the mantelpiece.

‘Yes,’ he said, nodding at it. ‘Quite a work of art. There can’t be many of them about.’

It was indeed a beautiful object. A narrow, tapering blade, and a hilt of elaborately intertwined metals of curious and careful workmanship. he touched the blade gingerly with his finger, testing its sharpness, and made an appreciative grimace.

‘Lord, what an edge,’ he exclaimed. ‘A child could drive that into a man – as easy as cutting butter. A dangerous sort of toy to have about.’

‘May I examine the body properly now?’ I asked.

He nodded.

‘Go ahead.’

I made a thorough examination.

‘Well?’ said the inspector, when I had finished.

‘I’ll spare you the technical language,’ I said. ‘We’ll keep that for the inquest. The blow was delivered by a righthanded man standing behind him, and death must have been instantaneous. By the expression on the dead man’s face, I should say that the blow was quite unexpected. he may have died without knowing who his assailant was.’

‘Butlers can creep about as soft-footed as cats,’ said inspector Davis. ‘There’s not going to be much mystery about this crime. Take a look at the hilt of that dagger.’

I took the look.

‘I dare say they’re not apparent to you, but I can see them clearly enough.’ he lowered his voice. ‘Fingerprints!’

He stood off a few steps to judge of his effect.

‘Yes,’ I said mildly. ‘I guessed that.’

I do not see why I should be supposed to be totally devoid of intelligence. After all, I read detective stories, and the newspapers, and am a man of quite average ability. If there had been toe marks on the dagger handle, now, that would have been quite a different thing. I would then have registered any amount of surprise and awe.

I think the inspector was annoyed with me for declining to get thrilled. he picked up the china mug and invited me to accompany him to the billiard room.

‘I want to see if Mr Raymond can tell us anything about this dagger,’ he explained.

Locking the outer door behind us again, we made our way to the billiard room, where we found Geoffrey Raymond. The inspector held up his exhibit.

‘Ever seen this before, Mr Raymond?’

‘Why – I believe – I’m almost sure that is a curio given to Mr Ackroyd by Major Blunt. It comes from Morocco – no, Tunis. So the crime was committed with that? What an extraordinary thing. It seems almost impossible, and yet there could hardly be two daggers the same. May I fetch Major Blunt?’

Without waiting for an answer, he hurried off.

‘Nice young fellow that,’ said the inspector. ‘Something honest and ingenuous about him.’

I agreed. In the two years that Geoffrey Raymond has been secretary to Ackroyd, I have never seen him ruffled or out of temper. And he has been, I know, a most efficient secretary.

In a minute or two Raymond returned, accompanied by Blunt.

‘I was right,’ said Raymond excitedly. ‘It is the Tunisian dagger.’

‘Major Blunt hasn’t looked at it yet,’ objected the inspector.

‘Saw it the moment I came into the study,’ said the quiet man.

‘You recognized it, then?’

Blunt nodded.

‘You said nothing about it,’ said the inspector suspiciously.

‘Wrong moment,’ said Blunt. ‘Lot of harm done by blurting out things at the wrong time.’

He returned the inspector’s stare placidly enough. The latter grunted at last and turned away.

He brought the dagger over to Blunt. ‘You’re quite sure about it, sir. You identify it positively?’

‘Absolutely. No doubt whatever.’

‘Where was this – er – curio usually kept? can you tell me that, sir?’

It was the secretary who answered.

‘In the silver table in the drawing-room.’

‘What?’ I exclaimed.

The others looked at me.

‘Yes, doctor?’ said the inspector encouragingly. ‘It’s nothing,’ said the inspector again, still encouragingly.

‘It’s so trivial,’ I explained apologetically. ‘Only that when I arrived last night for dinner I heard the lid of the silver table being shut down in the drawing-room.’

I saw profound scepticism and a trace of suspicion on the inspector’s countenance.

‘How did you know it was the silver table lid?’

I was forced to explain in detail – a long, tedious explanation which I would infinitely rather not have had to make.

The inspector heard me to the end.

‘Was the dagger in its place when you were looking over the contents?’ he asked.

‘I don’t know,’ I said. ‘I can’t say I remember noticing it – but, of course, it may have been there all the time.’

‘We’d better get hold of the housekeeper,’ remarked the inspector, and pulled the bell.

A few minutes later Miss Russell, summoned by Parker, entered the room.

‘I don’t think I went near the silver table,’ she said, when the inspector had posed his question. ‘I was looking to see that all the flowers were fresh. oh! yes, I remember now. The silver table was open – which it had no business to be, and I shut the lid down as I passed.’