this had not been noticed, showed also that they had
not seen the bag opened. They would have been watching him if they
had; clearly the bag had been carried out of the car during his
absence, and later had been brought back. He set it on the floor
between his knees and checked over its contents. Nothing had been
taken, so far as he could tell; for the bag had contained only
clothing, the Chinese dictionary and the box of cigars, and these all
apparently were still there. He had laid out the things on the seat
across from him while checking them up, and now he began to put them
back in the bag. Suddenly he noticed that one of his socks was
missing; what had been eleven pairs was now only ten pairs and one odd
sock.

The disappearance of a single sock was so strange, so bizarre, so
perplexing that--unless it was accidental--he could not account for it
at all. No one opens a man's bag and steals one sock, and he was quite
sure there had been eleven complete pairs there earlier in the day.
Certainly then, it had been accidental: the bag had been opened, its
contents taken out and examined, and in putting them back, one sock had
been dropped unnoticed. The absence of the sock, then, meant no more
than that the contents of the bag had been thoroughly investigated. By
whom? By the man against whom the telegram directed to Lawrence
Hillward had warned Eaton?

Ever since his receipt of the telegram, Eaton--as he passed through the
train in going to and from the diner or for other reasons--had been
trying covertly to determine which, if any one, among the passengers
was the "one" who, the telegram had warned him, was "following" him.
For at first he had interpreted it to mean that one of "them" whom he
had to fear must be on the train. Later he had felt certain that this
could not be the case, for otherwise any one of "them" who knew him
would have spoken by this time. He had watched particularly for a time
the man who had claimed the telegram and given the name of Hillward;
but the only conclusion he had been able to reach was that the man's
name might be Hillward, and that coincidence--strange as such a thing
seemed--might have put aboard the train a person by this name. Now his
suspicions that one of "them" must be aboard the train returned.

The bag certainly had not been carried out the forward door of the car,
or he would have seen it from the compartment at that end of the car
where he had sat smoking. As