What do Ántonia, Lena, and Mary do the night of d’Arnault’s performance that they know is wrong, but that they thoroughly enjoy anyway?

They visit a negro piano player. Blind d'Arnault senses that there are girls dancing in the other room, and the men open the doors and invite Ántonia, Lena, and Tiny, who are listening on the other side of the wall, to come in. The girls are pretty, and Blind d'Arnault plays until they have to close the hotel.