In Paris in 1894, a young woman voluntarily allowed herself to be locked up in the Salpêtrière hospital in order to look for her mother. A ball is being prepared there.

Paris, in 1894. Every year, on the occasion of Carnival, an event popular with all of Paris is held in a psychiatric hospital. Politicians, artists and socialites crowd in front of the doors of this institution reserved for women, eager to participate in the infamous "Bal des Folles". Inside, 150 extravagantly disguised "crazy women" wait apprehensively. They were selected from among the 4,500 patients. Among them, Fanni, 35 years old. Unlike other women, most of whom are interned unfairly and against their will, she is here voluntarily. His only goal: to find his mother and escape with her.—allocine