It is a spin-off novel to the Fudge series, being set shortly after Tales of a Fourth Grade Nothing, and centers on Peter Hatcher's nemesis, Sheila Tubman, and her family.

Her family decides to spend summer in Tarrytown, New York, where she is enrolled at a day camp and meets Merle "Mouse" Ellis, an easygoing, courageous, and slightly tomboyish girl skilled with deep knowledge of yo-yo tricks.

Sheila believes that her fearless masquerade is effective, but her beliefs are proven false after the guests at her sleepover write otherwise in a slam book activity.

Despite the brawl that ensues between them, devastated by the insults written in each other's books, their friendship, nevertheless, continues, and Sheila slowly overcomes her fears (albeit not entirely) little by little.

As summer draws to a close with a barbecue, she is unshaken at the thought of her family's adoption of a puppy, and realizes that she enjoyed her vacation after all.

Libby Tubman - Sheila's thirteen-year-old sister, an aspiring dancer who is boy crazy and fancies herself to be quite sophisticated and glamorous, even calling her parents "Mother" and "Father".

One chapter deals with her sneaking into her own house through the milk door so the girls can play hide and seek when bad weather precludes them from doing so outdoors.

Sheila describes Sondra as being a little on the plump side, but prefers her over Jane, who is said to dunk people at the community pool.

The Tubmans later see a letter from him expressing his disdain at having a girl in his room and announcing he acquired a bunch of model planes and ships which he will take back home.

Peter Hatcher - Shiela's classmate and star of the preceding book, only seen when he shares an elevator ride with her and his dog, Turtle, whom she fears.