"Then we must take that as our working hypothesis. Young West
took the papers. Now this could only be done by having a false
key--"

"Several false keys. He had to open the building and the room."

"He had, then, several false keys. He took the papers to London
to sell the secret, intending, no doubt, to have the plans
themselves back in the safe next morning before they were missed.
While in London on this treasonable mission he met his end."

"How?"

"We will suppose that he was travelling back to Woolwich when he
was killed and thrown out of the compartment."

"Aldgate, where the body was found, is considerably past the
station London Bridge, which would be his route to Woolwich."

"Many circumstances could be imagined under which he would pass
London Bridge. There was someone in the carriage, for example,
with whom he was having an absorbing interview. This interview
led to a violent scene in which he lost his life. Possibly he
tried to leave the carriage, fell out on the line, and so met his
end. The other closed the door. There was a thick fog, and
nothing could be seen."

"No better explanation can be given with our present knowledge;
and yet consider, Sherlock, how much you leave untouched. We