There is no doubt that Valentine Besson, appreciated by all her neighbors in the Norman village of Étretat, is a charming old woman: fragile, petite, with a rosy complexion and fine features. The relationship with her main relatives, however, is more complex: her children and her daughter-in-law seem to resent her for having squandered the fortune of her late husband, a successful pharmaceutical industrialist, and forcing them to lead a modest life in which one day it was his second residence on the coast. When Rose, Mrs. Besson's maid, is poisoned, the old woman, convinced that she is the true target of the crime, decides to ask Commissioner Maigret for help, who, in order to solve the case, will have to bring to light the best kept secrets of this fishing community.