With its terrifying backdrop of falling guillotine blades, the end of Poulenc's 'Dialogues des carmélites' is a musical experience like no other. Soprano Rosemary Joshua shares her memories of this operatic horror show. Plus, listeners' picks of chamber music by Schumann and Beethoven, songs from the gifted baritone Benjamin Luxon, and the vocational highlight of any car horn virtuoso: Gershwin's 'An American in Paris'. With Chi-chi Nwanoku.