July 13, 1808. It is 15 years later to the day, when Napoleon is Emperor of France and the revolutionary fervor has died down now that France is in the ascendancy as a world-power, even while things are pretty much the same for its citizens that still have their heads attached. In the asylum of Charleton, one of its inmates, the Marquis DeSade takes advantage of some revolutionary therapeutic techniques to stage the murder of Marat with the inmates of the asylum acting out all the parts. An audience of gentry are invited to observe the performance behind bars, while the asylum's director uses the opportunity to curry favor and talk up the sanitarium's accomplishments through its advanced therapies, demonstrating them by holding the performance in the facility's hydrotherapy chamber.
What could possibly go wrong?
The play goes well after the director's flowery and self-congratulatory introduction, the inmates escorted to the "stage," Marat is played by a paranoiac (Ian Richardson), Corday by a woman (Glenda Jackson) suffering from narcolepsy, the chorus commenting in verse and in song are all done up in clown face, and the Marquis (Patrick Magee) sits sullenly, feigning civility and docility, while putting his invective into the script.
Oh, the layers. It's a film of a play within a play. We are an audience watching (and standing in for) an audience, who could be considered either in front of or behind bars. The play itself is a historical drama with commentary and interjections from the author who inserts himself frequently in the narrative. And the dynamic of jailers overseeing the production of mad-men reflects the government thinking themselves in charge of an unruly mob, a revolution has been mollified, after all, and the right people are in charge in a France that is stronger than ever, led by the proverbial man on a white horse.
Oh, what one could say if one wanted to be pedantically current. But, one could find undercurrents of all sorts of transitions and "revolutions" in the discussions in Marat/Sade—how, for awhile, when things get bad, the public spontaneously combusts, worries the power-brokers about their handle on things, things get better and go back into a torpor as the crowd is satiated with their bread and circuses. Nothing much changes but attitude. And maybe some budgets to be allowed to "trickle-down."
But the play is a microcosm of revolution. De Sade was once a revolutionary, but by the time of play's events, he's found another way. at various times, protests are made of the script and the asylum director steps in to say that things have gone too far, names should not be named to avoid scandal and the Marquis symbolically rips up the script to appear to allow the play to keep going. Because the play is the revolution. To allow it to go on keeps the flame of anarchy alive until such a time as spark can flame and everything descends to chaos.
Not even Napoleon could control that.