What a din along the boulevards on the day when the newsboys shouted: "Arrest of Arsene Lupin!"My excuse for duplicating reports that we all heard from the newsboys is that I can supply something new: I can furnish the key to the puzzle. There is always a certain mystery about these adventures: I can dispel it. I reprint articles that have been read over and over again; I copy out old interviews: but all these things I rearrange and classify and put to the exact test of truth. My collaborator in this work is Arsene Lupin himself, whose kindness to me is inexhaustible. I am also under an occasional obligation to the unspeakable Wilson, the friend and confidant of Holmlock Shears.