An Unusual End to an Expedition for Napoleon’s Treasure

Learning that the entire possessions of Piccolo, a man who taught Lupin about thievery when he was a young punk, have all been impounded by the police, Lupin and company go to see what they can do. Madame, his widow, knows nothing of her husband's true profession, believing him to be a musician, which means one big headache.

Synopsis excerpt via Kitsu.