I laid my hand on his shoulder. ‘Don’t try to think, Sir Arthur,’ I said gravely. ‘Be content—to forget.’

He looked at me in a puzzled way and nodded. I heard Phyllis draw a breath of relief. We had reached the house.

‘By the way,’ said Sir Arthur suddenly, ‘where’s the mater?’

‘She has been—ill,’ said Phyllis after a momentary pause.

‘Oh! poor old mater!’ His voice rang with genuine concern. ‘Where is she? In her room?’

‘Yes,’ I said, ‘but you had better not disturb—’

The words froze on my lips. The door of the drawing-room opened and Lady Carmichael, wrapped in a dressing-gown, came out into the hall.

Her eyes were fixed on Arthur, and if ever I have seen a look of absolute guilt-stricken terror I saw it then. Her face was hardly human in its frenzied terror. Her hand went to her throat.

Arthur advanced towards her with boyish affection.

‘Hello, mater! So you’ve been knocked up too? I say, I’m awfully sorry.’

She shrank back before him, her eyes dilating. Then suddenly, with a shriek of a doomed soul, she fell backwards through the open door.

I rushed and bent over her, then beckoned to Settle.

‘Hush,’ I said. ‘Take him upstairs quietly and then come down again. Lady Carmichael is dead.’

He returned in a few minutes.

‘What was it?’ he asked. ‘What caused it?’

‘Shock,’ I said grimly. ‘The shock of seeing Arthur Carmichael, the real Arthur Carmichael, restored to life! Or you may call it, as I prefer to, the judgement of God!’

‘You mean—’ he hesitated.

I looked at him in the eyes so that he understood.

‘A life for a life,’ I said significantly.

‘But—’

‘Oh! I know that a strange and unforeseen accident permitted the spirit of Arthur Carmichael to return to his body. But, nevertheless, Arthur Carmichael was murdered.’

He looked at me half fearfully. ‘With prussic acid?’ he asked in a low tone.

‘Yes,’ I answered. ‘With prussic acid.’

Settle and I have never spoken of our belief. It is not one likely to be credited. According to the orthodox point of view Arthur Carmichael merely suffered from loss of memory, Lady Carmichael lacerated her own throat in a temporary fit of mania, and the apparition of the Grey Cat was mere imagination.

But there are two facts that to my mind are unmistakable. One is the ripped chair in the corridor. The other is even more significant. A catalogue of the library was found, and after exhaustive search it was proved that the missing volume was an ancient and curious work on the possibilities of the metamorphosis of human beings into animals!

One thing more. I am thankful to say that Arthur knows nothing. Phyllis has locked the secret of those weeks in her own heart, and she will never, I am sure, reveal them to the husband she loves so dearly, and who came back across the barrier of the grave at the call of her voice.