I have enjoyed several Leblanc titles very much (Confessions of Arsene Lupin and Extraordinary Adventures of Arsene Lupin), but this is a weaker entry in the series. The book opens up with a robbery and a murder. Gentleman thief, Arsene Lupin, is implicated and amateur sleuth, Isidore Beatrelet, matches wits against him. But just when he thinks he has Lupin's methods figured out, Lupin proves that he is still ten steps ahead of him.
Unfortunately, the story goes on forever... (It was first serialized in a French magazine and it seems like Leblanc was adding things or making them up as time went along.) The plot is more convoluted than the others I've read. The whole history of the hollow needle and how its secret had been passed down for generations, then lost, then found by Lupin never really rang true for me.
When Lupin arranges for the kidnapping of the two detectives (Ganimard and Holmlock Shears) to prevent his own capture, it seems like bad form. And when he threatens, pleads and cajoles, it doesn't ring true to his persona. What happened to his gallantry, sophistication, and self-conceit?
Sometimes the translation seemed off, like when Lupin calls Beautrelet "baby." (Possibly a too literal translation of "mon enfant"?) Also, when Beautrelet is close to solving the case, he says, "I'm burning! I'm burning!" (That may make sense in French, but it's not very good English.)
Although I didn't enjoy this novel as much as the short stories, I don't plan to give up on Arsene Lupin just yet. Especially since a dozen of his titles are free for Kindle.