t 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?"

"I think so," Merrick said modestly. "Now, Mr. Skidmore had a
compartment to himself. He was locked in the very last thing, and nobody
joined the train afterward. Naturally a--well--an amateur detective like
myself wanted to know who was in the adjoining compartments. Three of
these could be dismissed at once. But in the fourth there was a
corpse----"

"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 u