Father-and-son lion tamers, Rabbas and Léo share a mistress - Rosita, the " lovely bitch " of the film's title. She is as wild as their lionesses and, in a single night the father is injured and the son attempts suicide. Only when Rosita leaves the circus can things get back to normal.

Sisif, a railwayman, saves a young girl named Norma orphaned by a train crash and raises her as his own daughter alongside his son, Elie. As she becomes an adult, Sisif grapples with whether to tell Norma the truth about her parentage.