Four little girls flee the cold concrete world of the housing project they live in, take refuge every evening in a house on an island in the middle of the Marne River. It is secret hideaway that no one should trespass. Unfortunately a big girl reveals everything to the schoolmistress and scandal breaks out. But it is Sophie, the youngest of the group, who gets suspected by her..."friends".

A beautiful and sophisticated teenager is placed in a regimented French girls' boarding school after her father apparently commits suicide over a business scandal. She immediately gains admirers -- a lustful middle-aged artist, a handsome young composer, a fellow female student -- as well as a jealous rival. With the help of her schoolmates, she attempts to elope with the composer, but the adults catch on to the plot, and she is locked into her room at night.