Locked in a train, a group of suicide candidates await the death promised them by a crook. When they have almost gone mad with anguish, the door opens.

The story begins at a concert during which Beethoven's Concerto in D major for violin and orchestra is performed. Romaine, a mysterious woman, is in the concert hall. Pierre, her husband, is first violin of the Orchester Colonne. That evening, she discovers Marcel, a brilliant concerto soloist, and falls in love with him. Pierre and Marcel are friends, which complicates the situation. Pierre invites his friend to the house, without suspecting what will happen. The young woman, trying to find a clever pretext for a one-on-one meeting, quickly reveals her feelings to Marcel.

Poorly educated by her father, a wacky researcher, Claudine is a teenager full of life who loves her small village school run by Miss Sergeant. A new teacher, Aimée Lanthenay, arrives at the school. Seemingly awkward, she is actually an arrivist who manages to get the departure of Miss Sergeant.