The Quimbys are in the living room, discussing Mrs. Quimby's soon-to-be-baby. Beezus suggests "Huckleberry" as a name if it's a boy, after Huckleberry Finn, pointing out that it needs a name, and wondering where the baby will sleep and whether Mrs. Quimby will need maternity leave. Mr. Quimby jokingly says that he likes "It" for a name, with the middle name "Is A", and Beezus suggests a name from Little Women. Mrs. Quimby suggests June for a girl, but Mr. Quimby points out that it's due in July and suggests Algernon for a boy. Ramona, meanwhile, is playing upside down, so Beezus chides her for being "weird".
Mr. Quimby calls the girls to lunch, and at the table, he goes over the plans for what will happen when Mrs. Quimby goes into labour. Then, he has Beezus give Mrs. Quimby the newspaper again, while he asks Ramona if something is bothering her. She responds in the negative, but he tells her that it's fine to be nervous or confused about the baby. Later, Mrs. Quimby, noticing that Ramona has been acting peculiar lately (although Ramona blames the hot weather), reassures her that new babies are important and Ramona won't lose her parents' love and attention when she stops being the youngest, but Ramona claims to know that already.
When Mrs. Quimby goes into labour, she tells Ramona to get Mr. Quimby, and then the parents leave for the hospital, leaving the girls home alone. They try to watch TV but Ramona doesn't like any of the available shows, so she decides to play a game, but Beezus thinks she's too old. The phone rings, and Beezus answers. It's Mr. Quimby, and Ramona wants to talk, but Beezus won't let her. Mr. Quimby said that "Algie's taking his time", so the girls lock the door and prepare for bedtime.
They begin doing the dishes, but Ramona wants to draw or call Mrs. Quimby instead. Beezus, however, insists that Ramona continue to help her with the dishes. Afterwards, Beezus tidies the living room and Ramona says that she wishes Mrs. Quimby were there. Beezus reassures her that it will all be fine, just like Ramona's own birth, which she doesn't remember clearly since she was only four at the time. However, to satisfy Ramona, she chooses spaghetti with tomato sauce at random when asked what she had for dinner.
In the bathroom, Ramona wonders why Beezus apparently ate tomato sauce, since she hates it. Beezus says that she might have liked it when she was four, prompting a conversation about which foods they like and dislike, and genetics. Mr. Quimby arrives home and reveals that the baby is a girl named Roberta Day Quimby.
The family goes to the hospital to visit the baby, but the nurse says that children under eleven are not allowed to visit the babies, as "small children might have contagious diseases". In the waiting room, Ramona worries that she may be coming down with something, causing her to feel itchy, which makes her scratch, which in turn causes an elderly couple to also fear that Ramona is ill. A doctor comes over and asks Ramona if she's okay, and she explains what happened. The doctor gives Ramona a checkup and diagnoses her with "sibling-itis".
Mr. Quimby and Beezus come back, but Ramona tells them she has some sort of "itis" and shows them the prescription. Mr. Quimby hugs her, which disturbs Ramona, since he may catch her germs. Beezus explains that "sibling" means a brother or a sister, causing Ramona to accuse her of giving her a disease. Mr. Quimby explains that it was just a jokey way of saying that Ramona was disappointed at not seeing Roberta.
At home, the older sisters set up Roberta's bassinet and wonder if she will cry a lot, and when Roberta comes home, she cries, causing the family to believe she is tired and put her down for a nap.
Differences from Book
- In this episode, Mr. Quimby actually wants to name his hypothetical son Algernon, however in the book, it was just a joke on the rhyme about Algie and the bear (since Mrs. Quimby looked bulgy, like the bear in the rhyme, when she was pregnant).
- In the book, the lower age limit for visiting newborns is twelve, but here it's eleven.
- In the book it was a single woman who mistook Ramona for ill, but in the show, a man (presumably the woman's husband) does too.
- The doctor who checks Ramona is male in the book and female in the show.
- In the book, Ramona knows the definition of "sibling", when in the show, she doesn't.