"The clue that will lead me to success. I am now treading firm soil, where I shall find marks and indications...."
"Cigarette-ashes?" asked Wilson, whom the interest of the situation was reviving.
"And plenty of other things! Just think, Wilson, I have discovered the mysterious link that connects the three adventures of the blonde lady. Why were the three houses in which the three adventures took place selected by Arsène Lupin?"
"Yes, why?"
"Because those three houses, Wilson, were built by the same architect. It was easy to guess that, you say? Certainly it was.... And that's why nobody thought of it."
"Nobody except yourself."
"Just so! And I now understand how the same architect, by contriving similar plans, enabled three actions to be performed which appeared to be miraculous, though they were really quite easy and simple."
"What luck!"
"It was high time, old chap, for I was beginning to lose patience.... This is the fourth day."
"Out of ten."