manufactured--so cleverly that it has defeated its own ends."

"How do you make that out?"

"Because, so long as the evidence against him was vague and
intangible, it was very hard to disprove. But, in his anxiety,
the criminal has drawn the net so closely that one cut will set
Inglethorp free."

I was silent. And in a minute or two, Poirot continued:

"Let us look at the matter like this. Here is a man, let us say,
who sets out to poison his wife. He has lived by his wits as the
saying goes. Presumably, therefore, he has some wits. He is not
altogether a fool. Well, how does he set about it? He goes
boldly to the village chemist's and purchases strychnine under
his own name, with a trumped up story about a dog which is bound
to be proved absurd. He does not employ the poison that night.
No, he waits until he has had a violent quarrel with her, of
which the whole household is cognisant, and which naturally
directs their suspicions upon him. He prepares no defence--no
shadow of an alibi, yet he knows the chemist's assistant must
necessarily come forward with the facts. Bah! do not ask me to
believe that any man could be so idiotic! Only a lunatic, who
wished to commit suicide by causing himself to be hanged, would
act so!"

"Still--I do not see--" I began.

"Neither do I see. I tell you, mon ami, it puzzles me. Me