When I arrived at Baker Street I found him huddled up in his armchair with updrawn knees, his pipe in his mouth and his brow furrowed with thought. It was clear that he was in the throes of some vexatious problem. With a wave of his hand he indicated my old armchair, but otherwise for half an hour he gave no sign that he was aware of my presence. Then with a start he seemed to come from his reverie, and with his usual whimsical smile he greeted me back to what had once been my home.

“You will excuse a certain abstraction of mind, my dear Watson,” said he. “Some curious facts have been submitted to me within the last twenty-four hours, and they in turn have given rise to some speculations of a more general character. I have serious thoughts of writing a small monograph upon the uses of dogs in the work of the detective.”

“But surely, Holmes, this has been explored,” said I. “Bloodhounds — sleuth-hounds —”

“No, no, Watson, that side of the matter is, of course, obvious. But there is another which is far more subtle. You may recollect that in the case which you, in your sensational way, coupled with the Copper Beeches, I was able, by watching the mind of of the child, to form a deduction as to the criminal habits of the very smug and respectable father.”

“Yes, I remember it well.”

“My line of thoughts about dogs is analogous. A dog reflects the family life. Whoever saw a frisky dog in a gloomy family, or a sad dog in a happy one? Snarling people have snarling dogs, dangerous people have dangerous ones. And their passing moods may reflect the passing moods of others.”

I shook my head. “Surely, Holmes, this is a little far-fetched,” said I.

He had refilled his pipe and resumed his seat, taking no notice of my comment.

“The practical application of what I have said is very close to the problem which I am investigating. It is a tangled skein, you understand, and I am looking for a loose end. One possible loose end lies in the question: Why does Professor Presbury’s wolfhound, Roy, endeavour to bite him?”

I sank back in my chair in some disappointment. Was it for so trivial a question as this that I had been summoned from my work? Holmes glanced across at me.

“The same old Watson!” said he. “You never learn that the gravest issues may depend upon the smallest things. But is it not on the face of it strange that a staid, elderly philosopher — you’ve heard of Presbury, of course, the famous Camford physiologist? — that such a man, whose friend has been his devoted wolfhound, should now have been twice attacked by his own dog? What do you make of it?”

“The dog is ill.”

“Well, that has to be considered. But he attacks no one else, nor does he apparently molest his master, save on very special occasions. Curious, Watson — very curious. But young Mr. Bennett is before his time if that is his ring. I had hoped to have a longer chat with you before he came.”

"Exactly!" he said, catching sight of an object made of polished metal. "Exactly! That's it!... Well, upon my word, it took me long enough!"

On the spot on the floor which he had uncovered lay the receiver of a telephone, the cord of which ran up to the apparatus fixed on the wall, at the usual height.

Lupin put the receiver to his ear. The noise began again at once, but it was a mixed noise, made up of different calls, exclamations, confused cries, the noise produced by a number of persons questioning one another at the same time.

"Are you there?... He won't answer. It's awful... They must have killed him. What is it?... Keep up your courage. There's help on the way... police... sol diers... "

"Dash it!" said Lupin, dropping the receiver.

The truth appeared to him in a terrifying vision. Quite at the beginning, while the things upstairs were being moved, Leonard, whose bonds were not securely fastened, had contrived to scramble to his feet, to unhook the receiver, probably with his teeth, to drop it and to appeal for assistance to the Enghien telephone-exchange.

And those were the words which Lupin had overheard, after the first boat started:

"Help!... Murder!... I shall be killed!"

And this was the reply of the exchange. The police were hurrying to the spot. And Lupin remembered the sounds which he had heard from the garden, four or five minutes earlier, at most:

"The police! Take to your heels!" he shouted, darting across the dining room.

"What about Vaucheray?" asked Gilbert.

"Sorry, can't be helped!"

But Vaucheray, waking from his torpor, entreated him as he passed:

"Governor, you wouldn't leave me like this!"

Lupin stopped, in spite of the danger, and was lifting the wounded man, with Gilbert's assistance, when a loud din arose outside:

"Too late!" he said.

At that moment, blows shook the hall-door at the back of the house. He ran to the front steps: a number of men had already turned the corner of the house at a rush. He might have managed to keep ahead of them, with Gilbert, and reach the waterside. But what chance was there of embarking and escaping under the enemy's fire?

He locked and bolted the door.

"We are surrounded... and done for," spluttered Gilbert.

"Hold your tongue," said Lupin.

"But they've seen us, governor. There, they're knocking."

"Hold your tongue," Lupin repeated. "Not a word. Not a movement."

He himself remained unperturbed, with an utterly calm face and the pensive attitude of one who has all the time that he needs to examine a delicate situation from every point of view. He had reached one of those minutes which he called the "superior moments of existence," those which alone give a value and a price to life. On such occasions, however threatening the danger, he always began by counting to himself, slowly - "One... Two... Three... Four.... Five... Six" - until the beating of his heart became normal and regular. Then and not till then, he reflected, but with what intensity, with what perspicacity, with what a profound intuition of possibilities! All the factors of the problem were present in his mind. He foresaw everything. He admitted everything. And he took his resolution in all logic and in all certainty.