"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."