The film depicts the Baron (in reality a major sponsor of Diderot) as a benign host and inventor of amusing machines, including a piganino.

Diderot's banned Encyclopédie is being secretly set up, printed and bound in a crypt beneath the chapel, where the noise of the presses is masked by the playing of an organ.

She has made a painting of Diderot's idol, Voltaire, and convinces him to be more daring and to pose for her in the nude, leading to an animated row with his wife Antoinette.

This unsavoury event is witnessed by a feared visitor, Baron d'Holbach's brother, the Cardinal, who is hunting for the illegal Encyclopédie printers.

However, she finally defects to Diderot's material and sensual causes, and the Cardinal fails to find the clandestine publishing operation which has been transplanted to Amsterdam.