In Chapter 80, the Villefort family continues to crumble after the attempted poisonings of the Saint-Merans and Barrois. At the close of the chapter, Villefort comes to a startling realization about his wife, which Dumas conveys using simile:

How odd it was! For all the confused feelings that he experienced on seeing [Valentine’s] tears, he also managed to observe Mme de Villefort; and it seemed to him that a faint, dark smile passed briefly across her thin lips, like one of those sinister meteors that can be glimpsed as they fall between two clouds against a stormy day.

As this simple smile flits across Mme de Villefort's face, it dawns on Villefort that she could potentially be the architect of this murderous plot, rather than his daughter, Valentine, who he had previously suspected. The simile of a meteor on a stormy day—a fleeting thing, gone as soon as it has appeared—illustrates the impossibly brief duration in which Mme de Villefort reveals her true intentions. Throughout The Count of Monte Cristo, Dumas uses metaphors and similes of stormy weather to explore the tumultuous inner lives of his characters. In this case, however, Mme de Villefort's inner life has revealed itself, disastrously, to her husband.