Celeste must imagine an innovative number to save the Rose Elephant, threatened with closure by the minister following the scandal. Arsène decided to go to America, but Augustine asked for her help to find Octave. Rose, meanwhile, takes risks by posing for an unknown artist from Montmartre despite the warnings of her sister.

Leon accepts that Céleste will accompany him to Saint-Loup to investigate the murder of his father. Octave and Arsène, in search of funds for their electric motor project, organize a clandestine boxing fight. Rose,who thought he knew Charles, discovered his true identity.

As she discovers inconsistencies about her father's death, Celeste is convinced that it is a murder and not a suicide. Rose, caught up in her past, is unmasked by Charles' mother. Arsène, helped by Octave, is trying to break a speed record to save his project and find investors.