Based on a true story set around turn-of-the-century France, it follows the lives of two men: Joseph Pujol and Dr. Marcel Baudouin. Pujol was an entertainer at the Moulin Rouge who was gifted with a unique backside, which could take in and release air in measured increments thus producing amazing and humorous noises. Dr. Baudouin was obsessed with Joseph's "instrument" and pursued him doggedly for many years, ultimately resulting in his undoing.