Professor Charles Buisson, astronomer and Nobel Prize winner, has just discovered a nova. He informs the other observatories by telephone. Just as he thinks one of them is calling back, he finds himself on the line with a young woman threatening suicide at the Ruban Bleu cabaret, if her lover hasn't joined her by midnight. Intrigued, the professor decides to go and prevent the unfortunate woman from committing suicide. One of his students, who earns her living as an understudy in a knife act, helps him in his investigation, while the school principal and a policeman suspect him of being a prankster or even of selling drugs. For the scientist, it's an opportunity to discover a world of music-hall that he'd never known before: "I thought I knew the sky chart by heart, but there's one planet that was totally unknown to me: Earth. I'll be back!
Professor Charles Buisson
Gisèle, student of Buisson
Lucien Mosca, boss of Ruban Bleu
Mrs. Rédéri
The determined trafficker
Pierre-Dominique, aka 'Pépé'
Maurice, Buisson's assistant
Patrice
Mrs. Buisson
Henriette, washroom attendant
The indecisive snob
Russian Princess
Woman from Paris
Poupette, presenter of the show
Woman from Paris
Woman from Paris
Woman from Paris
Woman from Paris
Woman from Paris
Woman from Paris
Cloakroom attendant
Florist
Inspector Corbin
Self
Self
Self
Self
Self
Self
Narrator
Magda, the pregnant dancer (uncredited)
Cowboy (uncredited)
Young female client of Ruban Bleu (uncredited)
Self (uncredited)
Self (uncredited)
Policeman at Quai des Orfèvres (uncredited)
Arsène the toothless (uncredited)
Woman with stomach ache (uncredited)
Police officer (uncredited)
Young customer of Ruban Bleu (uncredited)