"Well, it might be so. Or—well, there is an alternative. Now to continue our review of the situation from the time that the quarrel, if there is a quarrel, began. The lady keeps her room, alters her habits, is not seen save when she drives out with her maid, refuses to stop at the stables to greet her favourite horse, and apparently takes to drink. That covers the case, does it not?"
"Save for the business in the crypt."
"That is another line of thought. There are two, and I beg you will not tangle them. Line A, which concerns Lady Beatrice, has a vaguely sinister flavour, has it not?"
"I can make nothing of it."
"Well, now, let us take up line B, which concerns Sir Robert. He is mad keen upon winning the Derby. He is in the hands of the Jews, and may at any moment be sold up and his racing stables seized by his creditors. He is a daring and desperate man. He derives his income from his sister. His sister's maid is his willing tool. So far we seem to be on fairly safe ground, do we not?"
"But the crypt?"
"Ah, yes, the crypt! Let us suppose, Watson—it is merely a scandalous supposition, a hypothesis put forward for argument's sake—that Sir Robert has done away with his sister."
"My dear Holmes, it is out of the question."
"Very possibly, Watson. Sir Robert is a man of an honourable stock. But you do occasionally find a carrion crow among the eagles. Let us for a moment argue upon this supposition. He could not fly the country until he had realized his fortune, and that fortune could only be realized by bringing off this coup with Shoscombe Prince. Therefore, he has still to stand his ground. To do this he would have to dispose of the body of his victim, and he would also have to find a substitute who would impersonate her. With the maid as his confidante that would not be impossible. The woman's body might be conveyed to the crypt, which is a place so seldom visited, and it might be secretly destroyed at night in the furnace, leaving behind it such evidence as we have already seen. What say you to that, Watson?"
"Well, it is all possible if you grant the original monstrous supposition."