The film centres on Léo, aged 49. Just as he is about to separate from his partner, with whom he lives in Nancy, he learns of the death of his biological father, whom he never knew. Needing to take a train to Italy to settle his father's estate, he spends a few days in Paris to take a look at his life. Through discussions with his activist daughter and encounters with ghosts from his past, he gradually begins to question his existence, and especially his relationships with women.

A famous french actor is poisoned and dies right in the middle of a play. Martin, an actor friend, is soon suspected by the police while being hunted by the mysterious organization which ordered the murder.

The mayor of Lyon, Paul Théraneau, is in a delicate position. After 30 years in politics, he is running out of ideas and is faced with a feeling of existential emptiness. To overcome this, Paul hires a young and brilliant philosopher, Alice Heimann. Then follows a dialogue between two diametrically opposed personalities who will turn their certainties upside down.