from Woolwich, and Admiral Sinclair to his arrival in London;
so Sir James is no longer a direct factor in the problem."

"Who was the other man with a key?"

"The senior clerk and draughtsman, Mr. Sidney Johnson. He is a man of
forty, married, with five children. He is a silent, morose man, but he
has, on the whole, an excellent record in the public service. He is
unpopular with his colleagues, but a hard worker. According to his own
account, corroborated only by the word of his wife, he was at home the
whole of Monday evening after office hours, and his key has never left
the watch-chain upon which it hangs."

"Tell us about Cadogan West."

"He has been ten years in the service and has done good work. He has
the reputation of being hot-headed and imperious, but a straight,
honest man. We have nothing against him. He was next Sidney Johnson
in the office. His duties brought him into daily, personal contact
with the plans. No one else had the handling of them."

"Who locked up the plans that night?"

"Mr. Sidney Johnson, the senior clerk."

"Well, it is surely perfectly clear who took them away. They are
actually found upon the person of this junior clerk, Cadogan West.
That seems final, does it not?"

"It does, Sherlock, and yet it leaves so much unexplained. In the
first place, why did he take them?"

"I presume they were of value?"

"He could have got several thousands for them very easily."

"Can you suggest any possible motive for taking the papers to London
except to sell them?"

"No, I cannot."

"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 v