should say that ours will be the only ones with any sense in them. We will take the research case, of course, and we may as well have a camera with us. I see there is a train from Charing Cross in twenty minutes."
For the first half-hour of the journey Thorndyke sat in his corner, alternately conning over his notes and gazing with thoughtful eyes out of the window. I could see that the case pleased him, and was careful not to break in upon his train of thought. Presently, however, he put away his notes and began to fill his pipe with a more companionable air, and then the inspector, who had been wriggling with impatience, opened fire.
"So you think, sir, that you see a way out for Ellis?"
"I think there is a case for the defence," replied Thorndyke. "In fact, I call the evidence against him rather flimsy."
The inspector gasped. "But the knife, sir? What about the knife?"
"Well," said Thorndyke, "what about the knife? Whose knife was it? You don't know. It was covered with blood. Whose blood? You don't know. Let us assume, for the sake of argument, that it was the murderer's knife. Then the blood on it was Pratt's blood. But if it was Pratt's blood, when the hounds had smelt it they should have led you to Pratt's body, for blood
