"Should I make an assault upon the castle at the head of a band of
adventurers as they did in ancient times?"

"That would be foolish."

"Can I gain admittance by stealth or cunning?"

"Impossible."

"Then there is only one way open to me. I must have the owner of
the castle invite me to it."

"That is surely an original method."

"And how easy! Let us suppose that one day the owner receives a
letter warning him that a notorious burglar known as Arsene Lupin
is plotting to rob him. What will he do?"

"Send a letter to the Procureur."

"Who will laugh at him, *because the said Arsene Lupin is actually
in prison.* Then, in his anxiety and fear, the simple man will
ask the assistance of the first-comer, will he not?"

"Very likely."

"And if he happens to read in a country newspaper that a
celebrated detective is spending his vacation in a neighboring
town---"