Yo-Yo Ma plays music composed by Ennio Morricone, best known for his scores for Spaghetti Westerns like "Once Upon a Time in the West". The cellist performs Morricone's iconic themes and melodies from his most famous film soundtracks. In three sentences or less, this summary provides the essential information that Yo-Yo Ma, a renowned cellist, performed music composed by Ennio Morricone, an acclaimed film composer best known for his Western film scores such as for the movie "Once Upon a Time in the West".