"The man's name was Arthur Cadogan West. He was twenty-seven
years of age, unmarried, and a clerk at Woolwich Arsenal."

"Government employ. Behold the link with Brother Mycroft!"

"He left Woolwich suddenly on Monday night. Was last seen by his
fiancee, Miss Violet Westbury, whom he left abruptly in the fog
about 7:30 that evening. There was no quarrel between them and
she can give no motive for his action. The next thing heard of
him was when his dead body was discovered by a plate-layer named
Mason, just outside Aldgate Station on the Underground system in
London."

"When?"

"The body was found at six on Tuesday morning. It was lying wide
of the metals upon the left hand of the track as one goes
eastward, at a point close to the station, where the line emerges
from the tunnel in which it runs. The head was badly crushed--an
injury which might well have been caused by a fall from the
train. The body could only have come on the line in that way.
Had it been carried down from any neighbouring street, it must
have passed the station barriers, where a collector is always
standing. This point seems absolutely certain."

"Very good. The case is definite enough. The man, dead or
alive, either fell or was precipitated from a train. So much is
clear to me. Continue."

"The trains which traverse the lines of rail beside which the