I knew it by certain precautions he took.

I knew it by certain words he let fall.

I knew it by the way he looked at unexpected strangers.

I was perfectly certain that he had some powerful enemies, that he believed they were on his track, and that he was always on his guard against them.

I was so sure of it that for years I have been terrified if ever he came home later than was expected." "Might I ask," asked Holmes, "what the words were which attracted your attention ?" "The Valley of Fear," the lady answered.