It's another special double episode, this one focusing on the world of opera and Christie's personal love of music. In our first story we attend Covent Garden with Mr. Satterthwaite and the mysterious Mr. Quin, while in the second it's a private theatrical extravaganza starring world-renowned prima donna Paula Nazorkoff. As anyone familiar with the plots of many an opera will know, it doesn't take long for things to get rather murder-y....