“He looked from one of us to the other, an expression of curiosity on his features. ‘I’m sorry to barge in on you without warning, Palfreyman,’ he said at last. ‘You appear a little preoccupied. But I wanted to discuss the exhibition at the British Museum with you.’

“‘That’s perfectly all right, Ainscow,’ returned the professor in an affable tone. ‘We were just discussing something. It’s nothing, really. We thought we heard someone out in the garden, that’s all. Do come in, old man. Will you stay for supper?’

“‘If it’s not too much of an imposition.’

“So Professor Ainscow dined with us that evening, and I must say I was glad he did, for his presence lightened the mood considerably. The two men continued their discussion for some time after supper, then Professor Palfreyman accompanied his colleague to the railway station. I was unsure whether this was out of courtesy to his guest, or because he wished to see if there was anyone loitering outside in the lane. When he returned, he looked a little agitated again, but this might simply have been the result of coming into the bright house from the dark lane outside.

“‘Did Professor Ainscow catch his train?’ I enquired.

“‘Yes, yes, he did,’ Professor Palfreyman replied, but in an abstracted tone, as if his mind were on something else. ‘Georgina,’ said he after a moment, ‘there is something I wish to tell you. However,’ he added, ‘I think I will wait until tomorrow. Thank you, by the way, for being such very good company at the supper table this evening. I am sure Ainscow was very glad he came. I probably shouldn’t tell you this, but he paid you a great compliment as we walked up the road. He said he thought you must be the prettiest assistant that any archaeologist had ever had, and if I ever felt that I no longer required your services, he would take you on like a shot.’

‘‘I laughed heartily at this, as much from embarrassment as humour, but the laughter died on my lips as I saw the professor’s grave face. ‘For my own shortcomings and failings, Georgina,’ he said, ‘I am very sorry. I sometimes think I may have outlived my usefulness in this world.’

“‘What nonsense!’ I cried, patting his arm. ‘Don’t say such things, Professor! Don’t even think them! What you need is a good night’s rest, and then I’m sure everything will seem better!’

“Alas! He might have needed a good night’s rest, but I don’t think he got one. I heard him talking to himself in his sleep in the small hours of the night, and it was clear he was experiencing a terrible nightmare, for his voice gradually grew louder and more agitated, though whether from fear or anger, I could not quite decide. Some of the phrases I heard him use were such as I had heard before: ‘Don’t look at it! For God’s sake, don’t look at the face!’ and similar exhortations.

“The following morning, the professor’s features bore a haggard look, but after a solid breakfast – which we ate largely in silence – and several cups of coffee, he seemed restored to his usual affable and urbane self. It was as I was about to leave the breakfast table that he spoke to me.

“‘Georgina,’ said he, in a kindly, thoughtful voice, ‘I will tell you now what has been weighing on my mind lately, and what I am going to do about it. I feel it is only fair to you. You have had to put up with a lot lately.’

“‘Not at all,’ I began, but he waved my protests aside.

“‘There are things in my past of which I am not especially proud,’ he continued after a moment, ‘and one thing in particular. This is not entirely a secret: most of the facts have always been known to my colleagues, to the relevant authorities and to anyone else who cared to enquire about the matter, but my thoughts – the thoughts I had at the time and have had since – are known to no one but me. They relate to some of the disturbances you have had to endure recently, Georgina. What I am therefore going to do is to write out a full, honest and accurate account of what happened, so that if – when – I die, you will be able to read it, and then you will understand everything.’

“‘Don’t talk like that, Professor!’ I interrupted. ‘I’m sure you have many good years ahead of you! You’d better have, for you haven’t yet finished even one of those three books you intended to write!’

“Professor Palfreyman smiled at me. ‘It is good of you to be so encouraging, Georgina! But I do sometimes wonder if I shouldn’t perhaps think of making way for the younger generation. I’m not sure I deserve to live any longer.’

“‘Nonsense!’

“‘This brings me to the other thing I wished to say to you. I know, from conversations we have had, that although of course you wished to care for your dear mother as well as you could, you nevertheless felt somewhat imprisoned in the house while you were doing so. You found life there very dull and tedious. You should know, then, that the very last thing I should ever wish upon you is that you should feel imprisoned in this house, Georgina. Much as I enjoy your presence here, you should not feel you have any duty to remain if you don’t wish to.’

“‘It is quite unnecessary for you to say these things,’ I responded. ‘I can assure you that the last year has been the happiest year of my life. If the remainder of my life were just half as happy, I should be more than satisfied.’

“‘It is kind of you to say so,’ said he, ‘but the fact remains that you are young, and may meet someone of your own age with whom you wish to spend the remainder of your life. In which case, I should not wish you to feel in any way restricted by the fact that I have found you such a pleasant companion here. I am not so selfish as that, and I do not wish you to think that I am.’

“‘If you are referring to Mr Martin,’ said I, ‘then I should tell you that he is simply a friend to me, and I certainly have no plans for our relations to be other than that. Besides, he himself has proposed nothing to me of the sort you suggest.’

“‘Perhaps not, and I express no judgement as to whether Mr Martin would or would not be a suitable candidate for you, Georgina, but I know that it is in his mind to make such a proposal to you. One man generally knows what another man is thinking so far as these matters are concerned.’

“‘Should he, or anyone else, ever make such a proposal to me, then I will let you know what my response is,’ I said. ‘Until then, I should prefer to drop the subject.’

“Professor Palfreyman laughed. ‘Very well!’ said he, ‘At least I have aired what I wished to air. Now let us be about our work!’

“That was last Thursday, and since then Professor Palfreyman has been scribbling away on his foolscap most of the time and has scarcely spoken to me except at mealtimes. He did go up to town on Friday morning on some errand or other, but I don’t know what for, as he didn’t tell me. It has been a strange few days. Dr Webb called in on Monday afternoon, and was very rude. When I happened to mention that Professor Palfreyman had been very busy lately, he retorted, ‘He’s not too busy to see me,’ which was not at all what I had meant, and when I took a cup of tea into the study for him, he completely ignored me. When he left, he did not say a word to me, despite the fact that I was standing in the garden when he walked down the path.

“Yesterday morning, Professor Palfreyman had another of those letters, containing a blank sheet of paper. This time I made no suggestion about invisible writing, or anything of the sort, and he simply tore it up and threw it on the fire. In the afternoon, I took some papers up to town for him, and as the train passed Herne Hill I happened to think of Mrs Walsh, an old acquaintance of my mother’s who used to live there. Then an occasion when she visited us came into my mind, when she had spoken in glowing terms of you, Mr Holmes. She said you had helped a neighbour of hers, Mrs Trubshaw, who had been receiving unpleasant anonymous letters.”