One by one, the smoking-room company faded away. Presently only Merrick and the Marquis remained, save one guest who had fallen asleep in his chair. A sleepy waiter looked in and vanished again. The hotel was absolutely quiet now. Merrick, however, was wide awake enough; so, apparently, was the Marquis. All the same, he yawned ostentatiously.
"Let us to bed," he said. "To-morrow, perhaps----"
"No," Merrick said somewhat curtly. "I prefer to-night. Sit down."
The last two words came crisply and with a ring of command in them. The Marquis bowed as he dropped into a chair and lighted a fresh cigarette. A little red spot glowed on either of his brown cheeks, his eyes glittered.
"You want to speak to me, Colonel?" he said.
"Very much indeed. Now, you are an exceedingly clever man, Marquis, and you may be able to help me. It happens that I am deeply interested in the Grand Coast Express murder; in fact, I have devoted the last two months to its solution."
"With no success whatever, my dear Colonel?" the Marquis murmured.
"On the contrary, my dear Marquis, with absolute satisfaction. I am quite sure that you will be interested in my story."
The Marquis raised his cigarette graciously.
"You are very good to give me your confidence," he said. "Pray proceed."
"Thank you. I will not bore you with any preliminary details, for they are too recent to have faded from your memory. Sufficient that we have a murder committed in an express train; we have the disappearance of eight thousand pounds in gold, without any trace of the criminal. That he was on the train at the start is obvious. That he was not in any of the carriages conveying ordinary passengers is equally obvious. It is also certain that he left the train after the commission of the crime. Doubtless you read the evidence of the guard to prove that nobody left the train after the viaduct leading to Lydmouth station was reached. Therefore, the murderer contrived to make his escape when the express was traveling at sixty miles per hour."
"Is not all this superfluous?" the Marquis asked.
"Well, not quite. I am going to tell you how the murderer joined the train and how he left it after the murder and the robbery."
"You are going to tell me that! Is it possible?"