"The Adventure of the Blanched Soldier" (1926) is one of the 56 Sherlock Holmes short stories written by Sir Arthur Conan Doyle. It was first published in The Strand Magazine October 1921 - April 1927 and is one of the stories in the cycle collected as The Casebook of Sherlock Holmes. This story is one of only two narrated by Holmes rather than Doctor Watson - the other one being "The Adventure of the Lion's Mane".
In January 1903, at 221B Baker Street, James M. Dodd sees Holmes about a missing friend, Godfrey Emsworth. Dodd and Emsworth served together in the Imperial Yeomanry in South Africa during the Second Boer War, which has only just ended. Emsworth was wounded. Dodd has not seen him since the report of his injury, and "not a word for six months and more". Since Emsworth has always been such a good friend, Dodd believes something is amiss.
Dodd tried writing to Colonel Emsworth, Godfrey's father. He had to write twice before he got an answer, and then was told in a terse letter that Godfrey was not at home; he had gone on a voyage around the world. Dodd was not satisfied with this explanation — he was sure that Godfrey would not simply go off around the world without telling his old army friend.
Next, Dodd went to the Emsworth family home, Tuxbury Old Park, near Bedford. There were four people there — the Colonel and his wife; and an old butler and his wife. The Colonel was something less than a gracious host. He repeated the story about his son's world voyage, implied that Dodd was lying about even knowing Godfrey, and seemed irritated at Dodd's suggestion that he provide information that would allow him to send Godfrey a letter. This the Colonel would not do.
Dodd was still determined to ascertain Godfrey's fate. That evening, in the ground-floor bedroom, Dodd talked to the butler, Ralph, when he came to deliver some coal. When Ralph mentioned Godfrey in the past tense, Dodd began to suspect that his friend was dead. Ralph indicated that no, he wasn't, but that it might be better that way.
If the butler's words had deepened the mystery, Godfrey's appearance at the bedroom window made it utterly bottomless. There he was, with his nose pressed against the glass, but looking ghastly pale. He ran off when he saw that Dodd was looking straight at him. Dodd opened the window and climbed out, thinking to go after him and put an end to this mystery. In the pathways of the park, he could not see where Godfrey had gone, but heard a door slam somewhere ahead of him, not back at the house.
Dodd contrived to stay another day at Tuxbury Old Park, and went looking about the property. He saw a well-dressed man leaving an outbuilding, whose suspicion was aroused somewhat, as Dodd was aware that he was watching him. The outbuilding seemed empty enough, but he was sure that it was where Godfrey had gone the previous evening.
After nightfall, he crept out of the bedroom window again and stole down to the outbuilding. Finding a crack in the shutters, he looked in, saw the man he had seen earlier in the day, and another figure who he was sure was Godfrey, although he could not see him clearly.
At this point came the tap on his shoulder. It was Colonel Emsworth, beside himself with rage, and he made it plain to Dodd that he was to leave on the first available train.
Dodd comes straight to Holmes to relate the story, and Holmes, as is often the case, finds the matter quite elementary. There are, after all, only a few reasons why a family would shut one of its members in an outbuilding. Holmes needs only to ask about the publication that the man with Godfrey was reading, and although Dodd cannot be absolutely sure of it, Holmes seems satisfied with the answer. Only one piece of evidence is missing.
Holmes has his missing clue that same day when he and Dodd visit Tuxbury Old Park, much to the Colonel's fury. The clue comes in the form of a tarry smell from the leather gloves that Ralph has just removed. The Colonel threatens to summon the police if Dodd and Holmes do not leave, but Holmes points out that involving the police would bring about the very catastrophe that the Colonel wishes to avoid.
Holmes makes it known that he has deduced that the mystery can be summed up in one word: leprosy. Upon visiting the outbuilding, Holmes and Dodd hear Godfrey's story right from his own lips. The night he was wounded in South Africa, he found his way to a house and slept in a bed there. When he woke up in the morning, he found himself surrounded by lepers. The doctor there told him that he was in a leper hospital, and would likely contract the disease after sleeping in a leper's bed. The doctor helped heal his wounds, and once Godfrey got back to England, the dreaded symptoms began to appear. His family's fear of their son's seclusion in an institution, and possibly the stigma attached to leprosy, have forced them to keep his presence secret.
The story ends happily, however. Holmes has brought with him Sir James Saunders, a famous dermatologist from London. Sir James determines that Godfrey in fact has pseudo-leprosy, or ichthyosis, something quite treatable.
Holmes's investigation of the mystery is delayed because he is engaged in clearing up "the case which my friend Watson has described as that of the Abbey School, in which the Duke of Greyminster was so deeply involved". The Duke of Holdernesse was the principal client in the case of the Priory School.