During the first part of the school year that is covered in The Wednesday Wars, Mr. Guareschi is the principal of Camillio Junior High School. When Holling accidentally lets Mrs. Baker’s rats out of their cage, the principal cautions them not to let anyone else know that the rats are loose in the building.

In November, as Holling is getting more accustomed to Mrs. Baker, he is assigned to help her with the pet rats she keeps in her classroom. A gift from her husband, they are named Sycorax and Caliban after two characters in William Shakespeare’s play The Tempest. Mrs. Baker assigns Holling the task of cleaning their cage after he creates a fiasco involving cream puffs and chalk dust. After he cleans their main cage, while he is trying to transfer them back from their temporary cage, however, he gets distracted by a comment the teacher makes. Ignored for a few seconds, the rats make a noisy commotion and Holling is afraid of getting bitten. They get loose and run out into the classroom.

Amidst all the chaos of trying to retrieve them, Mrs. Baker is concerned that they not be injured. She sends Hollis for Mr. Vendleri, the maintenance man. After they fail to catch the rats using brooms and the rats escape into the dropped ceiling, she concludes that she must notify the principal. Mr. Vendleri brings him from his office to the classroom.

Once the principal fully grasps the situation, he becomes about appearances and possible panic. He cautions all of them not to let anyone know that the rats are loose in the building:

Not a soul hears outside of this room hears about the incident ... Not. One. Soul.

Hollis terms the ensuing efforts to find and capture them “Mr. Guareschi’s Campaign Against the Escapees.”