hester set the example. They noticed that the visitor
was without the handbag which had hitherto seemed a part of his
personality. Self-possessed and vaguely smiling, he spoke in an easy,
pleasant voice:

"Of course you are surprised to receive a call from me." He addressed
Alvin, who replied:

"I don't deny it. Heretofore you have seemed more anxious to keep out of
our way than to meet us."

"I admit that it did have that look, but the cause exists no longer."

This remark did not enlighten the youths. Chester for a time took no part
in the conversation. He listened and studied the man while awaiting an
explanation of what certainly had the appearance of a curious proceeding.

"I don't understand what could have been the cause in the first place,"
said Alvin, "nor why my friend and myself should have been of any
interest at all to you."

The other laughed lightly, as if the curt remark pleased him.

"I have no wish to play the mysterious; my name is Stockham Calvert."

It was Alvin's turn to smile, while Chester said meaningly:

"That tells us mighty little."

"I am one of Pinkerton's detectives."

The listeners started. They had never dreamed of anything of this nature,
and remained silent until he should say more.

"You are aware," continued the mild spoken caller, "that there have been
a number of post office robberies in the southern part of Maine during
the last six months and even longer ago than that."

The boys nodded.

"A professional detective doesn't know his business when he proclaims his
purpose to the world. He does so in the story books, but would be a fool
to be so imprudent in actual life. Consequently you will think it strange
for me to take you into my confidence."

"I don't doubt you have an explanation to give," suggested Alvin.

"I have and it is this. Without any purpose or thought on your part you
have become mixed up in the business. The other night you gave me great
help, though the fact never entered your minds at the time. You located
their boat in a small inlet at the southern extremity of Barter Island."

At this point Chester Haynes asked his first question:

"How do you know we did?"

Mr. Stockham Calvert indulged in a low laugh.

"Surely I did not follow you thither without learning all you did. Your
conversation on the steamer gave me the information I wished. I did not
expect you to succeed as well as you did."

"Why did you avoid us? Why didn't you take us in