The book is about an 8-year-old warmhearted schoolgirl named Mayzie McGrew who one day suddenly sprouts a bright white daisy from her head. It causes alarm in her classroom, family, and town, until an agent makes her a celebrity. Mayzie becomes overwhelmed and distraught over the situation and runs away. The Cat in the Hat, who serves as the narrator to this story, helps Mayzie to understand her problem. He persuades her to go back home, and the daisy eventually goes away, popping up back again on occasion. The book has a mini-song titled "Daisy-Head Mayzie" which her classmates chant.