The narrative centers on a dramatic confrontation in a school classroom, where the oppressive headmistress, Miss Trunchbull, attempts to intimidate her students. Miss Trunchbull arrives with a hostile demeanor, threatening the children with "exceptionally unpleasant" consequences if they cross her. She singles out a student named Lavender, demanding she recite the three times table backwards. When Lavender fails, Trunchbull resorts to verbal abuse, calling her a "blithering idiot," "festering gumboil," and a "moth-eaten maggot."
The tension peaks when the chalk begins to move on its own across the blackboard. The chalk writes a message addressed to "Agatha" (Trunchbull’s first name), claiming to be from "Magnus." The spectral message demands that Trunchbull "give my Jenny back her house" and "give my Jenny her wages." This supernatural intervention causes Trunchbull to collapse, "out cold," marking the end of her reign of terror. As the text notes, she "marched out of the school building" and "vanished," never to return, allowing justice to be restored.
Following Trunchbull’s mysterious departure, the legal situation regarding the "red house" is resolved through the discovery of "Magnus's will." Miss Honey, previously downtrodden and impoverished, reclaims her rightful home. Matilda visits Miss Honey in her beautiful garden, where they reflect on the miraculous events. Miss Honey acknowledges that she "wouldn't be here if it weren't for" Matilda, highlighting the profound impact of their bond and the successful "trick with the chalk."
Matilda reveals a significant development: she has lost her telekinetic powers. She notes that when she tried to move objects, "nothing moved" and "the power had gone." Miss Honey provides a rational, psychological explanation for this phenomenon. She suggests that Matilda’s powers were the result of "tremendous energy bottled up in your brain" because she had "nothing to make you struggle" in her previous class.
Now that Matilda is in the "top form," competing against older, more advanced students, her "mental energy is used up in class." Miss Honey expresses relief at this transition, stating, "I wouldn't want to go through life as a miracle worker," and reinforces the idea that Matilda has "done enough."
The story concludes with a heartwarming exchange between the mentor and the student. Matilda, having moved on from her extraordinary feats, engages in a mundane conversation about biology, asking, "Did you know that the heart of a mouse beats at the rate of 650 times a minute?" This shift from the supernatural to the scientific signifies that Matilda has successfully transitioned from a "miracle worker" into a normal child, finding peace in her intellectual growth and her enduring friendship with Miss Honey.