An English mother and her teenage son spend a week packing up the contents of their remote holiday house in the South of France. Fifteen-year-old Elliot (Alex Lawther) struggles with his dawning sexuality and an increasing alienation from his mother, Beatrice (Juliet Stevenson). She in turn is confronted by the realisation that her marriage to his father, Philip, has grown loveless and the life she knows is coming to an end.

When an enigmatic local teenager, Clément (Phénix Brossard), quietly enters their lives, both mother and son are compelled to confront their desires and, finally, each other. Departure is an intimate story beginning at dawn on the first day and ending at night on the sixth, charting the end of a summer, the end of a childhood and the end of an otherwise nuclear, middle-class family.