Watson Solves a Case

Lestrade: The reason I called you, Mr. Holmes, is so that you can reassure my superiors that Sir Edward died of natural causes.

Holmes: I'm not sure I can do that, Inspector. From examining the body, I think that Sir Edward was poisoned.

Lestrade:  At first, I was under the same impression. However, the coroner found no trace of poison in the body. That's when I though of you. Could there be some rare poison that we wouldn't have detected?

Holmes: There are a few poisons derived from rare South American frogs that London coroners wouldn't know about. But before conjecturing further, were there any needle marks on Sir Edward's body?

Lestrade: I see what you're getting at Mr. Holmes. If Sir Edward was poisoned, how was it administered? My thoughts exactly. The coroner swears there were no needle marks, so we are sure the poison had to be in something he ate or drank--and there's the problem. Sir Edward died at a party. He  ate from the same buffet table as everyone else. If his food was poisoned, why weren't any of the other guests sick? If his drink was poisoned, why didn't we find any traces of poison in Sir Edward's glass?

Holmes: It's very tempting to assume that Sir Edward died of natural causes. Why are your superiors so bent on thinking that he was murdered?

Lestrade: Well, he had been acting strangely lately, and he has many enemies. In fact, just before going to the party, he met with one of his worst enemies, James Moriarty, at Moriarty's club. But Moriarty couldn't have poisoned him because the only thing Sir Edward had at the club was an appetizer that he shared with Moriarty. It couldn't have been the appetizers because Moriarty didn't get sick--and we didn't find any trace of poison when we tested the appetizers.

Holmes: In my bones, I know that Moriarty is behind Sir Edward's death, but I' m afraid I don't know how he did it. What do you make of this, Watson?

Watson: It reminds me of one of the first patients I had when I was in India. Things were very chaotic during the war, so patient records were often incomplete. I took over a private's case because his physician had died earlier in the day. I administered a perfectly safe drug to the young private--perfectly safe unless the patient has been given quinine. The combination of the two drugs creates an interaction that is invariably lethal. Unfortunately, unbeknownst to me, the soldier's previous doctor had been treating the lad for malaria with quinine. So, when I administered my drug, the private died.

Holmes: Brilliant, Watson! You've solved the case. Lestrade and I have been fooled because we were considering only  the main effects of drugs. The main effect of the drug Moriarty gave Sir Edward must be negligible, and the main effect of what Edward consumed at the party--probably alcohol--is also nonlethal. But the interaction between the two drugs is fatal. What fiendish brilliance! But we have him now, Watson. I have a list of drugs that interact with alcohol to produce death. I'll have the coroner look for the presence of these drugs in the body and in the appetizers from Moriarty's club. It's a pity we didn't discover this earlier--we could have offered Moriarty a brandy.


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