The piece much played throughout the film is Brahms' transcription for left hand of the chaconne from Johann Sebastian Bach's Violin Partita in D minor, performed by Warner Bros. pianist Victor Aller.
Mr. Aller made a piano arrangement for the left hand of the Chaconne from J. S Bach's Violin Partita in D minor, and, according to a press release, he spent 200 hours training actor Victor Francen in proper technique.