“The only reality is imagination,” the Marquis de Sade sneers, as ominous towers loom above his head and his fellow inmates of the Charenton Asylum surround him. They twitch and convulse in their post-French Revolutionary garb replete with modern accessories-their fishnet stockings and combat boots.

This is not your typical period production-it’s a rehearsal of Emerson Stage’s wonderfully warped version of Peter Weiss’ 1964 play, Marat/Sade.

The play is a compound of the legacy of two notable figures of the French Revolution: Jean-Paul Marat and the Marquis de Sade. The Marquis, an erotic writer, was a patient at the Asylum from 1803 until his death in 1814. At the hospital, de Sade wrote plays, and as a form of “art therapy” the other inmates performed them.

In Marat/Sade, the Marquis has written a play about the assassination of the revolutionary Jean-Paul Marat. Marat, who spent his last days writing denunciations on the National Assembly as he sat in his bath to relieve an unknown yellowing skin disease, was stabbed by Charlotte Corday on July 13, 1793, exactly 15 years before Marat/Sade’s setting.

Imagination is key in this play-within-a-play, where the actors are the inmates and the members of the audience are visitors to the asylum. It is never truly known where the Marquis’ script ends and “real life” begins.

As the sounds of “Children of the Revolution” flood the Greene Theatre during a rehearsal of Marat/Sade, the patients begin to writhe. A toy trumpet announces the Marquis’ arrival to the stage, carrying the unconscious Charlotte Corday, played by a patient who suffers from sleeping sickness. Coulmier, supervisor of the Asylum, enters with his wife and daughter to watch the play the Marquis has prepared for them. The patient playing the role of Marat sits in his bathtub in the middle of the stage.

Nightmarish shadows, punk flourishes and paint-splattered walls together generate a sense of insecurity. It is immediately apparent that this play will not have a typical happy ending. It is the acting, though, that keeps the audience wriggling in their seats, uncertain of what will happen next.

Dan Perrault, the patient playing the character of Jean-Paul Marat, certainly commands attention. Marat could be seen as weak and pathetic, but Perrault gives him a strong representation. His force is a counter to the situation Marat is in-lying in a bathtub all day, constantly requiring medical attention and writing letters that appear to have no effect on the political state of France.

During each speech Marat makes, he stands in the bathtub tall and proud. His arms flail dramatically as he preaches his radical ideas and message of revolution. Perrault’s interpretation adds a sad-yet-comedic element to Marat who, despite being passionate about his cause, is entirely helpless.

Claire Morrison’s natural portrayal of the murderess, Charlotte Corday, is touching, yet disturbing. Her voice is filled with exhaustion, and her body moves so fluently it appears as if she is floating on air. She loses this ethereal aura when she begins to flog de Sade with a switch he stole from Coulmier. The sounds of the whip tearing at the Marquis’ back cause her eyes to open wide in surprise and excitement. It is this scene that harkens back to de Sade’s idea that sexual pleasure can be obtained through inflicting pain on others.

Leading the pack of bizarre individuals is Nick Ronan as the infamous Marquis de Sade. From the moment he strides onto the stage and takes his place in the velvet-backed chair to the final vibration of his cynical laugh after Marat’s assassination, Ronan commands the action in the room. It is obvious from his intense stares and slinky, cat-like movements, that he has no problems filling the Marquis de Sade’s shoes. His presence on stage is uncomfortably captivating and one cannot help but be ensnared by his mesmerizing voice.

The other characters are aware of this strange magnetism as well. At one point, using only his tongue and eyes, de Sade seduces Coulmier’s respectable wife standing a few feet away. Despite all efforts to despise Ronan’s de Sade, it’s impossible not to be drawn in by his unusual charm.

As Charlotte whips the Marquis, he says, “When I vanish, I want all traces of my existence to be wiped out.” However, Ronan’s performance as the Marquis is one not easily forgotten.

The combination of solid principal performances, the support of a talented ensemble, creative costumes and an eerie set make this claustrophobic play both entertaining and entrancing.

Under the direction of Magda Romanska, Emerson’s production of Marat/Sade is wicked and alluring. Filled with haunting chants, striking attire and a sinister environment, the play leaves the audience with a strangely sickening feeling in the pit of their stomachs, although it is not a displeasing feeling, but one of dark pleasure. In the spirit of the Marquis, sometimes a little perversion is a good thing.

Marat/Sade’s performances will run from Thursday through Saturday at 8 p.m. as well as a Saturday matinee at 2 p.m.