fashioned house in a very excellent neighborhood.

The girl meantime entered the house and delivered the letter to an old
lady--the same old lady who had been robbed. The latter said, as the
girl entered the room to the left of the hall:

"What! you have an answer already?"

"Yes, aunty."

The old woman took the letter, opened it and read:

"MADAM: I saw your advertisement. I will call upon you. When a card
is presented with the name of the undersigned you will know it is
the detective.

"Yours,

"OSCAR DUNNE."

"Well, I declare," exclaimed the old lady; "he will call on us."

"But how will he know where to call, aunty; you did not give your
address in the advertisement."

"That is so. I had forgotten that. Why, how will he know where to call.
I fear I have made a mistake. A man who is as big a dunce as that can be
of no service to us."

"But wait, aunty, these men sometimes have dark and mysterious ways of
their own for finding out facts. Let's wait and see if he does call."

Even as the girl spoke there came a ring at the door bell, and a few
minutes later a servant presented a card on which was the name, "Oscar
Dunne."

"Why, Alice, he is here; it's wonderful."

"Will you see him?"

"Yes."

"Alone?"

"Yes, retire, my child."

The niece retired and a few moments later Oscar was ushered into the old
lady's presence.

CHAPTER IV.

DUDIE DUNNE LISTENS TO A STRANGE STORY AND ENTERS
UPON A TRAIL THAT LEADS TO MANY VERY STARTLING
ADVENTURES.

"I am surprised to see you here."

"Is that so, madam?"

"Yes."

"Why should you be when you expressed a desire to see me?"

"When did I express such a desire?"

"The desire was implied in your advertisement."

"But I did not put my address in the advertisement. How did you
establish my identity?"

The detective smiled and said:

"It was a very simple matter, madam."

"I do not understand it."

"I will explain."

"Please do."

"We detectives are compelled to be very careful in all our movements. We
have enemies who are constantly seeking to trap us."

"What has all that to do with the fact that you knew my address?"

"I read your advertisement."

"Yes."

"I did not know whether it was genuine or a decoy sent out by the
thieves who robbed you."

"But even that does not explain how you obtained my address."

"By a very simple plan, madam."

"Tell me your plan."

"I mailed the letter to you."