Berenger is in his room asleep and having a nightmare. Dudard comes to visit him, but Berenger does not recognize his voice. Berenger is paranoid that his voice may be changing and that may be turning into a rhinoceros, but Dudard assures him that he is normal. They discuss Jean, but Dudard seems unsurprised. He chides Berenger, "you mustn't dramatize the situation," and tells him, "try not to think about it."
To explain the situation, Dudard suggests that this trend of humans becoming rhinoceroses is like influenza or perhaps madness. No matter what Dudard's reasoning, however, Berenger does not accept anything about the rhinoceros trend as logical or rational. Dudard tells him to "accept the situation," but Berenger simply cannot.
The scene turns when Dudard reveals that Mr. Papillon has turned into a rhinoceros as well. Berenger is outraged. Dudard claims that he does not support the rhinoceroses, but he does defend Papillon's apparent choice to become one. At this point, the characters are speaking about the rhinoceroses as though they are a political party.
Berenger and Dudard continue to argue about the rhinoceroses. Dudard considers himself objective, logical, and scientific. Berenger defends his arguments by saying, "I feel it intuitively." When they walk to the window and see outside that the Logician has turned into a rhinoceros, Berenger takes this to prove that Dudard's "logic" means nothing at all. Dudard takes it to mean that there must be a good reason to become a rhinoceros.
Daisy arrives and brings news that Botard has become a rhinoceros. Apparently his last words were, "we must move with the times!" In Daisy's report from the outside world, she indicates the now commonplace presence of rhinoceroses: "Nobody seems surprised any more to see herds of rhinoceroses galloping through the streets. They just stand aside, and then carry on as if nothing had happened."
Daisy prepares lunch for the three characters, but the sounds of rhinoceroses become overwhelming. They look out the window to see droves and droves of animals—and no humans at all. At this point, Dudard remarks that he is not hungry for lunch and that he would rather eat outside on the grass. He further declares that he prefers "the great universal family to the little domestic one." Berenger argues firmly that "man is superior to rhinoceros" and that "your duty is to oppose them, with a firm, clear mind." But Dudard does not listen. He soon runs off into the herd. Immediately, he becomes a rhinoceros and cannot be distinguished from the rest of the herd.
Alone, Berenger and Daisy find momentary peace. Berenger declares his love for Daisy, and although she does not return his affection with equal passion, she does seem to look forward to a happy life together. As they imagine this future of reading books and taking long walks, they engage in a philosophical discussion in which Daisy decides that they are "comparatively better than most. We're good, both of us...Guilt is a dangerous symptom." Berenger seems to agree with her.
The phone rings. For a moment, they almost choose not to answer it. When they do, they hear rhinoceros trumpeting on the other line. They turn on the radio and again only hear trumpeting. It now becomes clear that the authorities have become rhinoceroses, and they may well be the only two humans left.
As Berenger continues to express his love, Daisy starts to take a more apathetic stance. "Let things just take their course," she says. "What can we do about it?" Berenger still contends that the rhinoceroses are "mad," but Daisy finds more sympathy for them: "we must try to understand the way their minds work, and learn their language." Berenger insists, "there is something we can do. We'll have children and our children will have children..." Finally Berenger implores her to "save the world," but Daisy replies with apathy: "Why bother to save it?"
Daisy becomes more and more enthralled by the rhinoceroses outside. She describes their trumpeting as singing, their movement as dancing, and their status "like gods." Then, abruptly, she exits.
Left alone on stage, the only remaining human in the world, Berenger delivers a powerful monologue. He begins with heartbreak at Daisy's exit. He is certain that "I'm staying as I am." But he loses sense of reality, asking existential questions such as, "What is my language? Am I talking French?" and "What do I look like? What?" He then, for the very first time in the play, sees beauty in the rhinoceroses. "Oh how I wish I looked like them... Their song is charming." He even tries to turn into a rhinoceros by making their trumpeting sounds and asking for a horn to grow—but he remains human. Then, suddenly, he snaps out of it. In the final lines of the play, Berenger declares that he will "put up a fight against the lot of them. I'm the last man left, and I'm staying that way until the end. I'm not capitulating!"
As the act opens, Ionesco draws obvious similarities to the opening of the previous scene. The stage directions note that the set of Berenger's room is extremely similar to that of Jean's room. Furthermore, as Dudard enters and Berenger does not recognize him, their dialogue is quite similar to the earlier exchange between Jean and Berenger. We realize that Dudard is going to become a rhinoceros.
In this final act, the historical side of Ionesco's allegory becomes quite clear. When Dudard talks with Berenger about the rhinoceros trend, his arguments echo the arguments made by Germans during the Nazi regime's rise to power. "It's only temporary," Dudard tells Berenger. "They're not doing any harm...I'm starting to get used to it." Indeed, Dudard's attitude represents the danger that comes with political or cultural apathy. He tells Berenger, "you must learn to be more detached."
We can see why Berenger is the only person to remain human. Unlike everyone else, Berenger actively fears becoming a rhinoceros ("I'm frightened of becoming someone else"). He cannot ignore the situation at hand, but his reaction is not to go along. Instead, he admits, "I can't get over it." He cannot believe Dudard's sentiment that "this is the situation and there's nothing you can do about it."
When Dudard decides to join the animals, he describes his "duty" to join his peers. Although Berenger argues that his duty is to oppose the rhinoceros, Dudard cannot resist the urge to fit in with the majority. By illustrating the human tendency to fit in by showing the draw to become a rhinoceros, Ionesco illustrates how absurd and dangerous that tendency can be. We cannot trust the seeming authority of the Logician, nor can we trust the seeming authority of a majority.
We see a similar transformation with Daisy. As she slowly shifts her perspective on the rhinoceroses, she becomes a different person in the course of minutes. The rhinoceros draw thus proves to be quick and effective once it begins, overcoming even the people who say they will resist it.
With both characters' transformations, Ionesco emphasizes the recurring theme of appearance versus reality. Dudard appeared to be smart, focused, and career oriented. Daisy was beautiful, intelligent, and caring, the object of Berenger's desires. But in both characters, their external virtues could not stand up to the desire to fit in with the majority.
When Daisy describes how society has accepted the rhinoceroses, Ionesco suggests how very strange realities can become accepted as true by society. With enough time or pressure, he suggests, people come to accept such atrocities as Nazi persecution. They capitulate to totalitarianism or fascism for a variety of illogical reasons. If people had only trained themselves to see through bad arguments and to stay true to good ones, they would not have been taken in. But when even the Logician is exposed as just another illogical man of the herd, what hope is there that an even mildly democratic public can sustain itself? The ancient political philosophers, it seems, were right that democracy and other seemingly healthy political forms can easily become tyrannies when they succumb to irrationality or the other vices of human nature.
Berenger stands in sharp contrast to all the others. He does not merely pledge to resist the pull; he dedicates himself to resistance. He briefly flirts with the idea of being a rhinoceros, but it seems that he is willing only to accept some of the external characteristics of the animal, such as the sounds it makes. But he simply cannot change his nature; he cannot be the individualist he really is and also fit in as a rhinoceros. The desire to be an individual trumps the rest.
Berenger’s final monologue proudly affirms the character's individuality and commitment to a moral code. As he declares his individuality and his resolve to fight, we hear the playwright's message most clearly. We are to focus on Berenger and approve of his resistance. We feel the call to engage politically and personally in society so that people do not become rhinos or get taken in by banality and false reasoning. If we do not take this responsibility, Ionesco warns, we easily will become dangerous, unintelligent animals.
At the same time, however, we now must confront the meaninglessness of everyday life. If everyday conversation is banal and illogical, and if efforts to understand and live well in the world end up in loneliness and absurdity, what is the thinking man of resistance supposed to do with himself every day? At the close of Act I, Berenger took another drink after talking to his friend about how he wanted to stop drinking. His point of view lacked hope, and he could not find a redeeming value in everyday, ordinary actions. At the close of the final act, Berenger emerges a strong, resilient fighter, a defender of his humanity and, indeed, the human race itself. He has something noble to do. In this heroic character transformation, Berenger answers the philosophical question that once plagued him. In order to find worth in his actions, it seems, one must believe in a cause and fight for it.
What about the rest of us? Are we to fight simply to preserve the rationality and respect we deserve as human beings? Do our causes have any goal beyond simply promoting the exercise of human rationality as an end in itself? If rationality is to contemplate something other than itself, Ionesco gives us only a few glimpses of places we might look. Friendship and love had motivated Berenger before. Yet, these goals cannot trump individuality, for we might find ourselves in the place of Mrs. Boeuf, who gives up on individuality in order to be with her husband. Whether or not it is absurd to end up cleaving only to oneself in an absurd world is an issue that Ionesco leaves us to contemplate on our own.