Les Belles Portes neighbourhood. Elsa is staying at her father's house while he is away on holiday, when her brother Jacques unexpectedly comes back from China.

In a large building in a Parisian district, Elsa lives alone. Her young neighbor Alice hears her playing the piano at home and enjoys it. Elsa suggests that she learn the piano and offers to play it at home, when she is not there. Alice thus gets into the habit of living in Elsa's apartment several times a week.