The film is a biography of Giuseppe Tomasi (Bouquet), the prince of Lampedusa, who is the author of Il gattopardo, one of the most influential Italian novel of XX century and is adapted on screen ...
He was born in 1896 into the decaying Bourbon aristocracy. His father was the prince of Lampedusa (an island off Sicily). The author-to-be would inherit the title in 1934, when his father died.