It all started the day Amy Anne Ollinger tried to check out her favourite book in the whole world, From the Mixed-Up Files of Mrs. Basil E. Frankweiler, from the school library. That's when Mrs. Jones, the librarian, told her the bad news: her favourite book was banned! All because a classmate's mum thought the book wasn't appropriate for kids to read.

Amy Anne decides to fight back by starting a secret banned-books library out of her locker. The battle of the books escalates when she engineers a campaign to challenge every book in the school library. Because once you ban one book, you can challenge them all under the most ridiculous of pretexts: The Lorax portrays the timber industry in a negative light! The mouse in the room in Goodnight Moon is a health code violation! And let's not even start on the safety concerns raised by The Magic Treehouse.

Soon, Amy Anne and her friends find themselves on the front line of an unexpected battle over book banning, censorship, and who has the right to decide what they can and can't read.