"A corpse! But there was no mention of that at the inquest."
"No, but the fact remains. A corpse in a coffin. In a dark compartment with the blinds down. And, strangely enough, the firm of undertakers who consigned, or were supposed to consign, the body to Lydmouth denied the whole business. Therefore, it is only fair to suppose that the whole thing was a put-up job to get a compartment in the coach that Mr. Skidmore traveled by. I am going to assume that in that coffin the murderer lay concealed. But let me give you a light—your cigarette is out."
"I smoke no more," the Marquis said. "My throat, he is dry. And then——"
"Well, then, the first part is easy. The man gets out of the coffin and proceeds to fill it with some heavy substance which has been smuggled into the carriage under the pall. He screws the lid down and presently makes his way along the footboard to the next compartment. An athlete in good condition could do that; in fact, a sailor has done it in a drunken freak more than once. Mind you, I don't say that murder was intended in the first instance; but will presume that there was a struggle. The thief probably lost his temper, and perhaps Mr. Skidmore irritated him. Now, the rest was easy. It was easy to pack up the gold in leather bags, each containing a thousand sovereigns, and to drop them along the line at some spot previously agreed upon. I have no doubt that the murderer and his accomplices traveled many times up and down the line before the details were finally settled. Any way, there was no risk here. The broken packing cases were pitched out also, probably in some thick wood. Or they might have been weighted and cast into a stream. Are you interested?"
The Marquis gurgled. He had some difficulty in speaking.
"A little dangerous," he said. "Our ingenious friend could not possibly screw himself down in the coffin after returning to his compartment. And have you perceived the danger of discovery at Lydmouth?"
"Precisely," Merrick said drily. "It is refreshing to meet with so luminous a mind as yours. There were many dangers, many risks to take. The train might have been stopped, lots of things might have happened. It would be far better for the man to leave the express. And he did so!"
"The express at top speed! Impossible!"
"To the ordinary individual, yes. But then, you see, this was not an ordinary individual. He was—let us suppose—an acrobat, a man of great nerve and courage, accustomed to trapeze work and the use of the diving net."
"But Colonel, pardon me, where does the net come in?"