Egyptologist and museum curator Pierre Guérande (Gabriel Signoret) has, at the age of forty-eight, married the young Denise (Andrée Brabant), but he begins to fear for the relationship when his wife's friend Irène de Tramont (Genevieve Williams) comes on the scene. Irène's friend Maurice Herbert introduces Denise to him, and it seems to Pierre that he's lost his love to a guy who is 'modern': not only does he dance the tango but he's a golf ace and teaches Denise how to play the game. Pierre begins to believe that he's yesterday's papers, only fit for the sexual scrapheap, and decides – much like the elderly Egyptian prince he knows so much about – that he has to perform a sophisticated suicide. But at an unexpected moment: he poisons one of his cigarettes, mixes them up, and he'll die at an unknown time.
The problem is that he has to be very wary of anyone else – such as his wife – touching any of his cigarettes. But when he's down to his last one – and he knows that that must be the lethal one – Denise starts to smoke it. He snatches it from her, but then learns the truth: Maurice has never been anything more than a friend, Pierre is a man of culture, and that doesn't necessarily have anything to do with youth as Denise loves him: in fact Pierre has been winding himself up a tree he can't climb down unless it's explained to him. For a silent movie, there are a large number of words.