The film is based on a novel of the same name by Ethel Lilian Voynich.
In nineteenth-century Italy, nobody knows that Arthur, a prominent revolutionary, is the illegitimate son of Cardinal Montanelli. Arthur confides in his priest that he belongs to a secret organization, but when the priest then reveals his confession, the members of the movement are arrested and Arthur is denounced as a traitor. Years later, Arthur—now known as ‘the Gadfly’—becomes the leader of the national liberation movement and sacrifices his life to the cause.
The film was restored in 2020