It is morning at the Royal Palms Hotel in St. Cloud, a town on the Gulf Coast. Chance Wayne wakes up next to the middle-aged woman with whom he has been traveling. Getting out of bed, he tries to cure his hangover while she goes on sleeping. As he does so, Dr. George Scudder knocks on the door and asks him why he’s returned to St. Cloud. Chance says that he heard his mother is ill—plus, he still has a girlfriend in St. Cloud. With this, he asks how Heavenly Finley is doing, but Scudder ignores him and says that his mother has already died. Because Chance never provides a valid address at which to reach him—he’s always traveling—he never got word about his mother’s passing. Chance turns the conversation back to Heavenly, but Scudder warns him against pursuing her, and asks if Chance received the letter he sent him after his last visit to St. Cloud. Chance says he didn’t, and Scudder says the letter instructed him to stay away from Heavenly because she went through an “awful experience” because of “past contact” with him. Now, Scudder informs him, Heavenly’s father has stated that he will have Chance castrated if he ever returns to St. Cloud. This doesn’t deter Chance, who asks Scudder to tell him more about what happened to Heavenly. Unmoved by Chance’s wish, Scudder says that he himself is engaged to be married to Heavenly.
Scudder leaves, and woman, called “the Princess,” begins to wake up. She can’t remember where she is, and asks Chance to tell her his name. Before long, she works herself into a panic, demanding that Chance fetch her oxygen mask. At this point, she and Chance have a long conversation in which Chance tries to jog her memory. There seem to be certain things she actively doesn’t want to remember, and when Chance references a “disappointment” she recently suffered, she claims to not recall it. “Can you control your memory like that?” he asks. “Yes,” she replies. “I’ve had to learn to.”
Eventually, the Princess reveals who she is and why she’s traveling with a young man like Chance, who is quite handsome despite the fact that his hair is thinning and his face looks “ravaged.” The Princess, the audience learns, is actually a famous actress named Alexandra Del Lago. Not long ago, she decided to make a comeback. On the night of her movie’s premiere, though, she saw her face on the big screen and was mortified by how old she looked. Worse, she heard people whispering behind her, wondering if the image could really be her. Because of this, she jumped up from her seat and ran, tripping on her way out and only exacerbating her embarrassment. As soon as she stood up again, she fled, and she hasn’t stopped running. Since then, she has been traveling under the pseudonym “Princess Kosmonopolis,” flitting between beach resorts, drinking heavily, popping pills, and smoking hashish to forget that her career has come to a harsh end. During her travels, she met Chance, who was working at a resort in Palm Beach. One day, he smelled hashish drifting from her room, followed the smell, and asked if he could join her for a smoke. Since then, he has been driving her around in her Cadillac, taking her from town to town.
As Chance and the Princess talk, Chance secretly sets up a tape recorder. He then rolls her a hashish joint and asks how she was able to get drugs into the country. She explains that she smuggled the hashish into the US on an international boat. After a while, Chance reveals that he has caught her admitting this fact on tape. Understanding that she has been blackmailed, she asks what he wants, and he reminds her that when they met in Palm Beach she signed a contract saying that a Hollywood studio—of which she owns a majority stock share—would cast him in a role. Even though she signed this contract and had it notarized, he still doesn’t trust her, so he has recorded her divulgence of incriminating information to ensure that she follows through with her word.
Chance also wants the Princess to throw a local beauty contest. Using her real name, she’ll attract a crowd, host the event, and then name Chance and Heavenly the winners. Then, he explains, she’ll call her studio and tell them she has found two actors to star in a movie about youth. Part of why he wants her to do this, he says, is because he needs to win over Heavenly’s father, Boss Finley. Boss Finley is a large political figure in St. Cloud, and he has never approved of Chance. Even though Chance and Heavenly have been in love for quite some time—since Heavenly was fifteen and lost her virginity to Chance—Boss Finley has refused to let them marry, believing that his daughter deserves a better man. As such, Chance has spent the last several years trying to become a famous actor so that he can return to St. Cloud and convince Boss to give him his blessing. Unfortunately, this plan has never worked out, and Chance has had to resort to working as a gigolo, sleeping with wealthy older women as a way of sustaining himself.
Hearing this, the Princess agrees to help Chance. However, she has one condition: whenever she wants to have sex, he must oblige. This is because sexual intercourse is the only effective way of getting her to forget her worries. Chance agrees to this, and after jumping back into bed with her to satisfy her needs, he leaves the hotel to drive around St. Cloud in her Cadillac, hoping to impress anyone who sees him passing by.
Meanwhile, Boss Finley speaks to Scudder about Chance’s return to St. Cloud. During this conversation, he references an operation Scudder performed on Heavenly after Chance’s last visit—an operation that should have been kept secret. To his dismay, people heard about the operation, and now a heckler brings it up every time Boss Finley has a political rally, which he is supposed to have tonight in the ballroom at the Royal Palms Hotel. Wanting Chance removed from town, Boss Finley fetches his son, Tom Junior, and tells him to do whatever it takes to get the job done. Boss criticizes Tom Junior for acting rowdily, but Tom defends himself by pointing out that he has organized the “Youth for Tom Finley club,” which is who will be attending the rally at the Royal Palms. He also suggests that his father isn’t so innocent himself, bringing up Boss’s longtime mistress, Miss Lucy. He then tells Boss that Miss Lucy recently wrote “Boss Finley is too old to cut the mustard” on a bathroom mirror in the Royal Palms Hotel.
Eventually, Boss Finley calls Heavenly to him and says he wants her to accompany him onstage at the rally. In fact, he wants her to wear the “stainless white” of a “virgin” so that people won’t speak badly about her and the operation she had. Despite his insistence, she protests, and they start arguing. Before long, though, Boss Finley embraces her and tells her that she’s “still” beautiful.
Later that day, Miss Lucy enters the lounge bar at the Royal Palms and tells Stuff—the bartender—about a fight she just had with Boss Finley. Soon after, Chance enters and Miss Lucy tells him he should leave St. Cloud, but he doesn’t listen. Then the heckler enters as well. After putting together that this man is the one who has been disrupting Boss Finley’s rallies, Miss Lucy decides to help him sneak into the ballroom when the time is right because she wants to spite Boss Finley after their argument.
In the time that elapses before the Youth for Tom Finley rally, the Princess comes downstairs looking haggard and confused. Chance runs over to her and tries to tell her to go upstairs again, but she says that she saw him out the window when he returned to the hotel in the Cadillac, and she could tell that he had failed in his attempt to impress the people he wanted to impress. She knows what this feels like—knows what it’s like to fail—and tries to convince him to leave with her. During this conversation, Tom Junior starts yelling at Chance to come outside and face him. He says that Chance gave Heavenly an STD last time he was in St. Cloud, and Chance reveals that he knew he had this disease but failed to say anything to Heavenly. As a result, Scudder had to perform an operation on Heavenly that left her sterile.
Boss Finley and Heavenly arrive at the hotel. Before her father can stop her, Heavenly rushes into the lounge, where she sees Chance and suddenly halts. The two of them stare at each other for a tense moment before Boss yanks Heavenly back, and a large crowd of Youth for Tom Finley supporters stream through the lounge and into the ballroom. Inside the ballroom, Boss Finley begins his speech. He talks about “pure white blood,” claiming that he was called upon by God to keep the white race from “pollution.” As he spews racist ideas—arguing against integration in the South—the heckler enters and yells about Heavenly’s secret operation. This incites mayhem, and people start to savagely beat him.
Not long after, the Princess stands at the window in her hotel room and looks out at the chaos that has broken out in the aftermath of the rally. Just then, Tom Junior and Dan Hatcher (the hotel’s assistant manager) come to her door and tell her she is no longer welcome at the Royal Palms because of her association with Chance. They then search the room for Chance. When they find nothing, they agree to help the Princess get a driver so she can escape. When they leave, Chance slips into the room, and the Princess tries to convince him that they should leave together. However, Chance is too stubborn to do this. Instead, he dials the number of a famous Hollywood reporter (one the Princess knows well) and tells the Princess to inform her that she has found two talented young actors: Chance and Heavenly.
When the Princess starts talking, though, the reporter tells her that her comeback film has been received well, and that everyone wants her to do another movie. Elated, the Princess ignores Chance as he hisses at her to talk about him and Heavenly. Eventually, she hangs up the phone and speaks excitedly about her return to the public eye. Before long, though, her optimism dips, and she begins to understand that the success of her comeback won’t change the fact that she no longer possesses the kind of youthful beauty required to make it in Hollywood. Feeling like this, she implores Chance once more to come with her, telling him that he has lost his youth and urging him to accept this fact and leave St. Cloud behind. As she stands to leave, Tom Junior and his goons appear in the doorway. Once more, the Princess asks Chance to come with her, and when he refuses, she finally leaves. Standing to meet his pursuers, Chance says, “I don’t ask for your pity, but just for your understanding—not even that—no. Just for your recognition of me in you, and the enemy, time, in us all.”