Victor Boniface's life is not exactly a rest cure. Just imagine: Victor is both a store detective and a ... shoplifter (only when he walks in his sleep, mind you)! And falling in love while sleepwalking is no bed of roses either, as the good-natured man simply forgets everything after waking up. Fortunately love wins the game in the end. Does that mean that life will become as easy as pie ? Certainly not: the little Bonifaces will be sleepwalkers just like their daddy!

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!