Lenormand operates as the alias Arsène Lupin assumes throughout the "813" narrative. He employs this concealed identity to investigate millionaire Rudolf Kesselbach's murder in Paris. Under the Lenormand guise, Lupin delves into the mystery of Kesselbach's death and its ties to geopolitical plots aimed at redrawing Europe's political map.

Lenormand's primary foe is the ruthless, near-superhuman assassin known as "L.M." or Malreich. Malreich ultimately exposes Lenormand as Lupin, resulting in Lupin's arrest. Incarcerated, Lupin persists in his pursuit from jail, manipulating events tied to the "813" affair.

Lenormand's actions constitute part of Lupin's overall strategy for the case. Following his exposure by Malreich, Lupin continues his quest from prison, engaging with external developments like the Kaiser's involvement and another detective's failure to solve the case.

The Lenormand alias defines a specific operational phase for Lupin within this storyline, ending upon the revelation of his true identity. Subsequent events, including Lupin's eventual release and the conclusion of the "813" affair, unfold after the Lenormand persona is discarded.