All the world knows the exploits of Arsène Lupin, man of mystery, adventurer, and private detective—when it suits him!

But now, a corner of the veil of mystery is lifted. For the first time, readers will find in this new adventure of the master-crook some indication of the Man behind the Mask. Arsène Lupin goes through life under a hundred aliases, a shadowy figure. But he is a human being like his fellows and can be moved by love and fear like other men.

As "Jean d'Enneris," Lupin finds himself engaged in a curious duel with his old opponent, Chief Inspector Béchoux. The Mélamare Mystery finds Lupin working both for and against the police—rather in his "Barnett" manner.