Modern Paris. The fire at Notre-Dame has unleashed an eerie force and awakened the ghosts of Victor Hugo's novel. Dr. Molendino, a jaded psychologist with a penchant for the occult, finds himself ejected from the clinical community for publishing controversial articles on the subject of past lives. To his colleagues he is a heretic, who compromises the prestige of the clinic.

After losing his job he immerses himself in private practice and research. Among his patients is Thomas Dimanche, a young journalist who suffers from dysmorphophobia and despite being handsome, considers himself hideous, avoiding human contact. Thomas makes a living by hosting a radio show called Parisian Toll, a criminal review, where he often features one of the city's most gruesome crimes — the murder of an indie performer Annaïs Guybertot. The teenage girl was found strangled in the basement of an underground nightclub aptly called Montfaucon.

With help from an experimental drug, the doctor and his patient dive into a hallucinatory world where a deformed bell ringer and his arrogant master rival for the heart of a gypsy dancer.

Will they stop in time, or will they repeat the fate of Hugo's characters?