Part Three of the novel begins in Chapter 35, with Grenouille arriving in the perfume-making town of Grasse. It took seven years for him to get from Paris to Montpellier; it took less than seven days to get to Grasse. He is hurrying to go to Grasse in order to find somewhere to learn about the other methods of distilling and preserving scent, which Baldini had told him about as he lay on his deathbed.
In this town Grenouille finds the scent of another red-headed girl, very like the one he killed in Paris on the rue des Marais. But this girl, he discerns only by smelling her outside her garden wall, is still a child, and already has an extraordinarily beautiful scent, which will mature in one or two short years into something utterly ravishing. Grenouille reflects on how people will think that her charm and fascination is in how she looks; Grenouille knows that the way she entrances everyone has very little to do with her looks and everything to do with her wonderful aroma.
Grenouille finds, on the rue de la Louve in Grasse, a small perfumer's workshop. The shop is run by the widow of a maître perfumer, helped only by a journeyman named Druot. Madame Arnulfi engages Grenouille on a very poor salary, but Grenouille is glad to have the work. Druot is Madame Arnulfi's lover, and he is only too happy to have someone do the hard work for him. Grenouille is put immediately to work making a pomade of jonquils with Druot. Grenouille learns not only how to make this, but also the processes of lavage and maceration, and the making of essence absolue--the most concentrated form of scent.
Grenouille shows himself to be such a good worker, and so quick to learn the intricacies of perfume-making, that Druot begins to leave more decisions to him. Grenouille learns the very finest way of collecting the most delicate scents--those of jasmine and tuberose—called cold enfleurage. Grenouille now knows that this method is best for the finest scents, and he begins to wonder about capturing the scent of the red-haired girl.
Grenouille slowly teaches himself to collect scents from objects other than flowers by the method of cold enfleurage. He starts with inanimate objects, such as doorknobs and stones, and then moves onto small animals. But he learns that animals do not give up their scents without a fight, and it is best to kill them first before extracting their odors. He experiments with capturing human odors by hanging oily cloths in a tavern and a church, but he finds that this is ineffectual for collecting pure human odors. Finally, he pays a deaf-mute beggar woman to wear the oily cloths next to her skin, which suggests to him the best method and the correct ratio of fats to collect the scent from a human being.
Madame Arnulfi marries Druot, but life at the workshop continues much as before. Grenouille visits the red-haired girl's street again, where he smells her improved scent through the garden wall. While he is closer to his goal, Grenouille starts to panic about the fact that, after he has killed the girl and collected her smell, the essence of her smell will eventually run out and can never be replaced. He becomes almost suicidal, but then a thought occurs to him. He will have to supplement this girl's scent with the scent of other human beings.
Grenouille starts killing girls in their first adolescence. The body of a fifteen-year-old-girl is found, naked and shorn of her hair, in a farmer's field. Grenouille took her clothes and hair in order to engage in cold enfleurage, after he had killed her by a blow to the back of her head. This is followed by two more murders of teenage girls, and the people of the region are thrown into a justifiable panic. As the murders continue, various groups are blamed and the authorities try various methods, including an anathema and excommunication. The murders abruptly stop as the count becomes twenty-four dead young women, and the people are relieved.
In Chapter 41, the father of the red-haired girl, Monsieur Richis (Antoine), is attempting to marry his daughter into the nobility. He has dynastic plans and, since he is a widower, he plans to marry again after his daughter's marriage so that he can have at least two sons to carry on his business and enter the law. He is less worried now that the anathema on the murderer seems to have worked, but he still guards his daughter, Laure Richis, carefully.
The reader now learns that Grenouille's goal, the red-haired girl Laure, has survived the murders. Grenouille has been killing other women to supplement the scent of Laure in his ultimate, ghastly human perfume. He is able to creep up on his victims and kill them soundlessly, for he finds and pursues them by scent, and he is not detectable by scent himself. All of Grenouille's preparation has been geared to this homicidal method of odor collection, and Grenouille's final goal becomes clear. He will create the ultimate human perfume from the essence of twenty-five young women's scents--a poetically satisfying round number--something that can only be obtained by means of their deaths.
The full brunt of the horror of Grenouille's true purpose is staggering. He is no longer just killing on the spur of the moment, as he had with the red-haired girl in the rue des Marais. Grenouille is stalking his kills, with the desire to collect their scents as his only motive. He has no regard for their humanity, but he harvests them as if they were flowers.
The introduction of Antoine Richis as a named character signals to the reader that his hubris, as the hubris of so many other characters in this novel, will bring him down. Richis, who is very rich and refined, is trying to rise above his bourgeois station and get himself and his children into the ranks of the nobility. To this end, he has waited for a nobleman to make an offer for his daughter's hand, even though she is now fully of marriageable age. He has not sent her away, as other families have done during the panic over the murders. Richis adores his daughter so much that he cannot bear to have him away from her.
The personalization of this family, who will be Grenouille's final victims, puts Grenouille's crimes in perspective. He is not just harvesting flowers for a scent. The surgical and fastidious murders of the previous twenty-four girls, and the resulting prejudiced hysteria, have made the situation seem darkly comic and have trivialized both the victims and the crimes. The focus has been on Grenouille's ingenious plans and the attainment of his goals. But the story of the murder of Laure will be more personal, because the readers will know the story of her family and her life.
Grenouille is very like the tick that he has been compared to several times in this novel. He waits silently and inconspicuously for the right time to drop on his victim. He learns all the necessary skills of the perfumer's art, so that he can collect the delicate scent of human beings, without Druot or anyone else ever suspecting him. He kills silently, choosing his victim only by scent, taking what he needs. Then he is gone, leaving not a trace of himself. In a sense, Grenouille has been preparing for this reasoned rampage all of his life, and it is the only thing that gives his life meaning, for he averts his desire for suicide only by taking on this new, grisly project to capture and extend Laure Richis' scent.