It was some time before the health of my friend, Mr. Sherlock Holmes, recovered from the strain caused by his immense exertions in the spring of ‘87. The whole question of the Netherland-Sumatra Company and of the colossal schemes of Baron Maupertuis is too recent in the minds of the public, and too intimately concerned with politics and finance, to be a fitting subject for this series of sketches. It led, however, in an indirect fashion to a singular and complex problem, which gave my friend an opportunity of demonstrating the value of a fresh weapon among the many with which he waged his life-long battle against crime.

On referring to my notes I see that it was on the 14th of April that I received a telegram from Lyons, which informed me that Holmes was lying ill in the Hotel Dulong. Within twenty-four hours I was in his sick room, and was relieved to find that there was nothing formidable in his symptoms. His iron constitution, however, had broken down under the strain of an investigation which had extended over two months, during which period he had never worked less than fifteen hours a day, and had more than once, as he assured me, kept to his task for five days at a stretch. The triumphant issue of his labours could not save him from reaction after so terrible an exertion, and at a time when Europe was ringing with his name, and when his room was literally ankle-deep with congratulatory telegrams, I found him a prey to the blackest depression. Even the knowledge that he had succeeded where the police of three countries had failed, and that he had out-manoeuvred at every point the most accomplished swindler in Europe, was insufficient to rouse him from his nervous prostration.

Three days later we were back in Baker Street together, but it was evident that my friend would be much the better for a change, and the thought of a week of spring-time in the country was full of attractions to me also. My old friend Colonel Hayter, who had come under my professional care in Afghanistan, had now taken a house near Reigate, in Surrey, and had frequently asked me to come down to him upon a visit.