ting seemed to increase his impatience almost beyond the bounds of
endurance. I saw him lean forward and gasp out a hurried word to the
postmaster, and was idly wondering over his anxiety and its probable
causes, when I heard a hasty exclamation near me, and looking around,
saw the postmaster himself beckoning to me from the door of the
enclosure. I immediately hastened forward.

"I don't know what it means," he whispered; "but here is a young man,
different from any who have been here before, asking for a letter
addressed to X. Y. Z."

"A letter?" I repeated.

"Yes, a letter."

"Give him the whole batch and see what he does," I returned, drawing
back where I could myself watch the result of my instructions. The
postmaster did as I requested. In another moment I saw the young man
start with amazement as a dozen letters were put in his hand. "These are
not all for me!" he cried, but even as he made the exclamation, drew to
one side, and with a look of mingled perplexity and concern, began
opening them one after another, his expression deepening to amazement as
he glanced at their contents. The one in the blue envelope, however,
seemed to awaken quite different emotions. With an unconscious look of
relief, he hastily read the short letter it contained, then with a quick
gesture, folded it up and thrust it back into the envelope he held,
together with the other letters, in his left hand.

"There must be another X. Y. Z.," said he, approaching the window of the
post-office and handing back all the letters he had received, with the
exception of the one in the blue envelope, which with a quick movement
he had separated from the rest and thrust into his coat-pocket. "I can
lay claim to none of these." And with a repetition of his easy bow he
turned away and hurriedly quitted the store, followed by the eyes of
clerks and customers, to whom he was evidently as much of a stranger as
he was to me. Without hesitation I went to the door and looked after
him. He was just crossing the street to the tavern on the other side of
the way. I saw him enter, felt that he was safe to remain there for a
few minutes, and conscious of the great opportunity awaiting me,
hastened back to the postmaster.

"Well," cried I, in secret exultation, "our plan has worked admirably.
Let me see the letters. As they have been opened, and through no fault
of ours, a peep at them now in the cause of justice will harm none but
the guilty."

The postmas