The Sound of Music is one of the most enduringly popular films ever made, yet behind it lays an even more astonishing family story. Sue Perkins travels to Salzburg, Ellis Island and Vermont to discover how the family made a living in America as the Trapp Family Singers and they eventually bought an estate in Vermont which looks uncannily like Austria. She also discovers that the ultimate feel good story has dark undertones, is disliked by Austrians, and witnesses the first ever performance of the musical in Salzburg itself.