In the short story Swan Song, Mr Cowan is the manager of the famous opera singer Paula Nazorkoff. A patient, long-suffering man very "accustomed to the vagaries of artistic temperament", he handles Nazorkoff's unpredictable behaviour with great skill. For her your in England, five performances for her at Covent Garden and a special performance at Albert Hall.
One unusual fixture is a request by Lord and Lady Rustonbury for a private performance of Madame Butterfly at Rustonbury Castle. Cowan encourages Nazorkoff to accept. It would be well worth the money, and there might many members of the aristocracy and even royalty present. It would be good advertisement. Nazorkoff agrees, but insists the opera must be Tosca. Despite the difficulties of setting Tosca up as a private show, Cowan successfully brings it about. What happens thereafter forms the main plot of the story.