Jean-Luc is an established gerontologist who can do no wrong; he runs a private clinic specializing in anti-ageing treatments. Honored for his work in this field, he throws a garden party at his home. It is during this social event that his father suddenly reappears, back after a long exile. A physician, he had left decades earlier without any apparent reason to practice in Africa. He moves into his son's home for several days, phlegmatically observing everything with an enigmatic smile. He peruses Jean-Luc's life and environment with cruel objectivity. The arrival of this "interloper" father, who everyone thought had disappeared for good, shatters the family microcosm: Jean-Luc doesn't know how to take him, as if the memory - or the resentment - was nothing but lost time; his wife becomes fond of this highly unconventional man; after first refusing to deal with him, Jean-Luc's younger brother strikes up a modest bond with him.