Plot: Tom Service invites us to listen to well-known, definitive masterworks from two of the greatest composers of all time with a fresh ear. Donald Runnicles takes on Beethoven's Fourth Symphony with the BBC Scottish Symphony Orchestra and joins forces with the National Youth Choir of Scotland and four top British soloists for Mozart's Requiem - a work of tragic beauty both musically and historically, left unfinished by Mozart just before his death in 1791