Arsène Lupin has settled in Rome as a painter named Arthur Lodin. Always on the lookout for new adventures, he occupies the apartment next door to the wealthy Marquis Belmonte. One day, he is mistakenly visited by a beautiful blonde woman who has come to see the marquis. A few moments later, Commissaire Gorgone bursts into Lupin's apartment. He searches for the young woman and declares her to be “Clara la blonde”, the accomplice of the notorious Italian thief Peppino. Lupin, who has just enough time to hide his visitor, leads the superintendent on a false trail.
