It was a clear and typical case of opium or morphine poisoning.

To this conclusion all his symptoms seemed to point with absolute certainty.

The coated tongue, which he protruded slowly and tremulously in response to a command bawled in his ear; his yellow skin and ghastly expression; his contracted pupils and the stupor from which he could hardly be roused by the roughest handling and which yet did not amount to actual insensibility; all these formed a distinct and coherent group of symptoms, not only pointing plainly to the nature of the drug, but also suggesting a very formidable dose.
But this conclusion in its turn raised a very awkward and difficult question.

If a large--a poisonous--dose of the drug had been taken, how, and by whom had that dose been administered?
The closest scrutiny of the patient's arms and legs failed to reveal a single mark such as would be made by a hypodermic needle.

This man was clearly no common morphinomaniac; and in the absence of the usual sprinkling of needlemarks, there was nothing to show or suggest whether the drug had been taken voluntarily by the patient himself or administered by someone else.
And then there remained the possibility that I might, after all, be mistaken in my diagnosis.