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!

Anthology film with three shorts each featuring a famous detective: Monsieur Wens, Lemmy Caution and Maigret.

Colette gives up her studies to become a cabaret dancer. She breaks with her fiance who does not approve of her choice.

A simple civil servant Léon, who has the unusual ability to walk through walls, falls madly in love with a hotel thief by the name of Susan. He poses as Garou-Garou, a dangerous gangster to attempt to woo her affections, but is arrested and sent to jail. While in jail he annoys the guards by walking in and out of his cell, and keeps persuading Susan to cease her criminal way of life. As fundamentally being an honest and law-abiding citizen, he eventually handles back everything he has stolen, is acquitted by the court, and becomes famous and respected. When he learns that Susan is planning to return to England and start a new life, he decides to confess to her his emotions. However, the couple is interrupted by a sudden rush of journalists. Trying to escape in a building, they get cornered on a corridor, and Léon pushes Susan through a nearby wall. But by doing this, he loses his own wall-walking ability, and the film concludes.