“What effect do you think it will have upon his plans now that he knows you are here?”

“It may cause him to be more cautious, or it may drive him to desperate measures at once. Like most clever criminals, he may be too confident in his own cleverness and imagine that he has completely deceived us.”

“Why should we not arrest him at once?”

“My dear Watson, you were born to be a man of action. Your instinct is always to do something energetic. But supposing, for argument’s sake, that we had him arrested tonight, what on earth the better off should we be for that? We could prove nothing against him. There’s the devilish cunning of it! If he were acting through a human agent we could get some evidence, but if we were to drag this great dog to the light of day it would not help us in putting a rope round the neck of its master.”

“Surely we have a case.”

“Not a shadow of one—only surmise and conjecture. We should be laughed out of court if we came with such a story and such evidence.”

“There is Sir Charles’s death.”

“Found dead without a mark upon him. You and I know that he died of sheer fright, and we know also what frightened him, but how are we to get twelve stolid jurymen to know it? What signs are there of a hound? Where are the marks of its fangs? Of course we know that a hound does not bite a dead body and that Sir Charles was dead before ever the brute overtook him. But we have to prove all this, and we are not in a position to do it.”

“Well, then, tonight?”

“We are not much better off tonight. Again, there was no direct connection between the hound and the man’s death. We never saw the hound. We heard it, but we could not prove that it was running upon this man’s trail. There is a complete absence of motive. No, my dear fellow; we must reconcile ourselves to the fact that we have no case at present, and that it is worth our while to run any risk in order to establish one.”

“And how do you propose to do so?”

“I have great hopes of what Mrs. Laura Lyons may do for us when the position of affairs is made clear to her. And I have my own plan as well. Sufficient for tomorrow is the evil thereof; but I hope before the day is past to have the upper hand at last.”

I could draw nothing further from him, and he walked, lost in thought, as far as the Baskerville gates.

“Are you coming up?”

“Yes; I see no reason for further concealment. But one last word, Watson. Say nothing of the hound to Sir Henry. Let him think that Selden’s death was as Stapleton would have us believe. He will have a better nerve for the ordeal which he will have to undergo tomorrow, when he is engaged, if I remember your report aright, to dine with these people.”