The song of the same name, later recorded by Édith Piaf and others, was written for this film by Hubert Giraud (music) and Jean Dréjac (lyrics).

Under the sky of Paris, during a day, we see large and small events that occur in the lives of several people whose fates will intertwine.

A poor old lady, after searching in vain all day to feed her cats, receives an unexpected reward from a mother whose daughter she had found.

A young girl, dreaming of love, refuses the advances of her childhood friend to be stabbed to death by a sadistic sculptor.

Rushed to hospital, the injured worker is saved through the first open-heart surgery performed by a young surgeon who has just failed his intern exam.