In the 1996 film adaptation of the Island of Dr. Moreau, starring Val Kilmer and Marlon Brando. Brando's character, Dr. Moreau, plays a duet with one of his deformed creations. What is the piano piece they are playing? What is the dramatic significance of the episode?
After some searching around finally found it:
Polonaise in A-flat major, Op. 53, by Chopin, known as "Heroic"
The piece is famous for being extremely difficult and is often included in standard repetoires of professional pianists to demonstrate their skill.
In the context of the movie, it demonstrates the mad Moreau's obsession with music and is emblematic of his misguided genius, playing on, oblivious to all, detached from reality of the monstrosity of the island.
(In the film, actor Brando is not actually piano, but just fingering the keys to a recording.)