The film stars Roy Dupuis, Clara Furey, Louis Negin, Jacques Nolot, Charlotte Rampling, Udo Kier, Gregory Hlady, Sparks,[3] Karine Vanasse, Adele Haenel, Mathieu Amalric, Maria de Medeiros and Geraldine Chaplin.

The film's frame story, and the narrative it returns to the most, concerns a submarine crew transporting a volatile substance that will explode if they ever resurface.

The most important of these "sub-stories" shows the woodsman and his fellow "sapling-jacks" trying to rescue a woman named Margot from depraved kidnappers.

Other sub-stories involve: a surgeon kidnapped by a team of "women skeletons" who work as insurance defrauders; a madman on a train under the charge of a womanizing psychiatrist; a mustache that seeks to comfort the widow of the man whose face it used to adorn; and a doctor cursed by a bust of Janus.

The final cut of the film is slightly shorter than it was on its world premiere at the Sundance Festival; the directors had to do some re-editing anyway, because the soundtracks on the DCP "were out of synch with each other."

The site's consensus states: "The Forbidden Room may frustrate viewers looking for a linear experience, but those seeking a challenge – or already familiar with director Guy Maddin's work – will be rewarded.