"The gentleman I describe."
"But who is he?"
"Surely it would not be difficult to find out. This is not such a populous neighbourhood."
Lestrade shrugged his shoulders. "I am a practical man," he said, "and I really cannot undertake to go about the country looking for a left-handed gentleman with a game leg. I should become the laughing-stock of Scotland Yard."
"All right," said Holmes quietly. "I have given you the chance. Here are your lodgings. Good-bye. I shall drop you a line before I leave."
Having left Lestrade at his rooms, we drove to our hotel, where we found lunch upon the table. Holmes was silent and buried in thought with a pained expression upon his face, as one who finds himself in a perplexing position.
"Look here, Watson," he said when the cloth was cleared "just sit down in this chair and let me preach to you for a little. I don't know quite what to do, and I should value your advice. Light a cigar and let me expound."
"Pray do so."
"Well, now, in considering this case there are two points about young McCarthy's narrative which struck us both instantly, although they impressed me in his favour and you against him. One was the fact that his father should, according to his account, cry 'Cooee!' before seeing him. The other was his singular dying reference to a rat. He mumbled several words, you understand, but that was all that caught the son's ear. Now from this double point our research must commence, and we will begin it by presuming that what the lad says is absolutely true."
"What of this 'Cooee!' then?"
"Well, obviously it could not have been meant for the son. The son, as far as he knew, was in Bristol. It was mere chance that he was within earshot. The 'Cooee!' was meant to attract the attention of whoever it was that he had the appointment with. But 'Cooee' is a distinctly Australian cry, and one which is used between Australians. There is a strong presumption that the person whom McCarthy expected to meet him at Boscombe Pool was someone who had been in Australia."
"What of the rat, then?"