“I cannot imagine how you intend to proceed in the case, Holmes,” I remarked at length, breaking the silence in the compartment. “The mystery surrounding Captain Reid appears utterly inexplicable.”

“There are one or two indications,” responded my friend, turning from the window and beginning to fill his pipe.

“If there are, then I confess I have missed them.”

“You have no doubt been pondering the matter overnight,” said he.

“I have certainly given it some thought,” I returned, “but can make nothing of it. It seems to me to be perfectly impenetrable!”

“Let us apply a little logical analysis, then,” said my friend as he lit his pipe, “and let our starting point be the one thing we know for certain: that the entire parish of Topley Cross appears, for some reason, to have turned against our client. We do not yet know what this reason might be, so let us, in the manner of mathematicians, call it ‘x’, the unknown, and see if we cannot, by reasoning around it, succeed in defining it a little more precisely. In the first place, whatever it is that has caused all these people to alter their opinions of Captain Reid must be considered by them a most serious matter. For surely only an occurrence of the utmost seriousness could have led them all – including, of course, Reid’s own father – to act in the way that they have done.”

“Well, that is fairly obvious,” I agreed.

“Yet Reid himself disclaims all knowledge of such an occurrence. Now, if the matter in question pertained to his military career, he would surely have heard something of it from his fellow officers in the regiment. We are therefore led to the conclusion that our unknown ‘x’ occurred in West Sussex, in the parish of Topley Cross. This is also indicated by the fact that whereas letters to Captain Reid from Topley Cross practically ceased after a short time, those from his sister in Cornwall did not. We must take it that she knows no more of the matter than her brother, and that during her stay at Oakbrook Hall at the time of her mother’s funeral, it – whatever it is – was not mentioned in her presence. As to ‘x’ itself, we must suppose that the facts of the matter are very clear, with evidence which appears to implicate Captain Reid directly, for we cannot think that his friends and family would turn against him on account, merely, of casual hearsay or local gossip.”

“That seems indisputable.”

“But here we encounter a difficulty. For it seems that when Captain Reid departed the area for India, his reputation was unblemished, his character unstained.”

“Whatever occurred, then,” I suggested, “must have occurred after he had left.”

“But how, then, can it reflect badly on Captain Reid? You see the difficulty, Watson? Clearly, it is not the date of the incident itself which is important, but the date when the facts came to light. Something occurred while Reid was still in England – otherwise he could not possibly be blamed for it – but did not become public knowledge until after he had departed, otherwise he would have become aware of it before ever he left the country. We can, I feel, date these events quite precisely. He received a friendly letter from Miss Blythe-Headley soon after his arrival in India. This must have been written within a week or so of his leaving. He replied, but heard nothing more. Some matter therefore came to public attention in Topley Cross approximately two weeks after his departure. We have thus narrowed down the place and the time quite precisely.”

“I cannot see that that helps us very much.”

“On the contrary, it helps us a great deal. To have established the place and time so closely will save us wasting our energies in irrelevant enquiry, and will undoubtedly help us to reach the truth much more speedily than would otherwise have been the case. Now we must address the nature of the problem itself.”

“There, I fear, we have nothing whatever to help us,” I observed. “Captain Reid has no idea what it is he is supposed to have done, and as no one, it seems, is prepared to tell him, we have nowhere to begin.”

“Come, come,” said my companion, smiling, “the matter is not quite so featureless as you suggest. In the first place, it cannot be that our client is believed guilty of an act that is criminal, or otherwise illegal, for we may suppose that if that were so, he would have long since been made aware of the fact by the authorities. Nor, on the other hand, can the matter be a trivial one, which might be soon forgiven and forgotten, since he remains subject to obloquy three years after the supposed date of the incident. Clearly, the censure to which he is subject is moral censure. We must therefore seek an act or series of acts which are generally held to be morally reprehensible – and seriously so – but which are not criminal in the strict legal sense of that term.”

“That leaves rather a wide field,” I remarked with a chuckle. “Most people’s idea of morality covers a very broad sweep of miscellaneous virtues and vices, great and small, but save for its sound provisions against murder and theft, the law of England chooses to concern itself with very few of them.”

“A wide field it may be,” returned Holmes, “but it is also an interesting field for speculation. We have also, let us not forget, the mysterious initials S. D. to help us in our enquiry. But, come! This next station is Pulborough, where we must take the branch-line train.”

The countryside through which the branch railway passed was a delight to the eye. On either side lay a multi-coloured patchwork of fields, and between them the bright autumnal hues of the hedgerows and spinneys. As if he had said all that he wished to say of his case for the moment, my companion began then to discuss the farming methods of the land’s first settlers, drawing numerous interesting observations to support his thesis from the landscape through which we were passing. He spoke almost as if he had made a special study of the subject, which surprised me very greatly, for I had never before heard him speak of anything save the ways of the denizens of London, and I had come to believe that his brain contained only such knowledge as was directly useful to his work, and which had its application strictly within a dozen miles of Charing Cross.

Presently, as our train pulled into a little rural station, its platforms brightened by tubs of flowers, Holmes sprang to his feet.

“Here I must leave you,” said he abruptly, much to my surprise. “The station for Topley Cross is the next but one, Watson. Take care of the bags, if you would, old fellow, and see if you can secure a couple of acceptable rooms at the best-looking inn you can find. I shall join you there later this afternoon.”

With no further word of explanation my companion was gone; the carriage door slammed behind him, and I was left to continue the journey alone. I did as he asked and took two rooms at the White Hart, a large, handsome old inn, which stood in the marketplace of Topley Cross. Then, I regret to record, although it was a beautiful autumn day, and I longed to walk to the end of the village and explore the countryside there, my illness overcame me. Tired by the journey from London, I lay exhausted upon my bed and soon fell into a deep sleep.

I was awakened by a tugging at my shoulder. Holmes was standing by my bed.

“I have made progress,” said he. “I have ordered a pot of tea, if you would care to come downstairs and hear the details.”

In a minute I was in the private sitting room of the inn and Holmes was giving me a sketch of what he had discovered.

“I have spent some time in the office of the local weekly newspaper,” said he, “where I was able to study the editions of three years ago. My hope was that I might uncover some suggestive fact there, some clue, however slight, to Captain Reid’s problem. I was prepared for a long and possibly fruitless search, and certainly could not have expected that success would be so swift. So narrowly, however, had we managed to define the time of that which has caused our client so much difficulty – our unknown ‘x’ – that in a matter of but a few minutes I was satisfied I had identified it beyond all possible doubt.” He took a long folded sheet of paper from his pocket and spread it out on the table before him, before continuing: “Upon Tuesday, 10 September 1878 – that is less than two weeks after Captain Reid sailed for India – a local girl, twenty years of age and well-known in Topley Cross, where she lived with her parents, was found dead. She had drowned in a pond about a mile from the village. Her name, Watson, was Sarah Dickens.”