When Amy Anne learns that her favorite book, From the Mixed Up Files of Mrs. Basil E. Frankweiler, along with a host of other works, has been removed from her school library she and her friends start the BBLL (Banned Books Locker Library) so that they can share the books with classmates who want to read them. As the book bans continue, and their beloved school librarian Mrs. Jones is replaced by a "shushing" imposter, they decide to fill out reconsideration requests for ALL the books in the library as a form of civil disobedience. They have no problem coming up with a reason for each book, from witchcraft to sexual content to violence to "it might confuse children", or in the case of a book of riddles, it might make kids feel bad if they can't figure out the answer. Never mind that it might make them feel good if they CAN figure it out.
Amy Anne is surprised to learn that there is a field of study called "library science" and enlists the help of Mrs. Jones to set up the BBLL. Mrs. Jones provides Amy Anne with some old equipment including a date stamp card. Once Amy has this she feels like a real librarian and only needed "a pair of glasses on a chain" to be ready for her "official librarian membership card."
One of the banned books is Judy Blume's classic work Are You There God? It's Me Margaret. Mrs. Jones explains that back in the day when due date stamps were used that libraries also used cards and pockets to keep track of who had checked out the books. She shows Amy Anne some old books that still have the cards and pockets. It is here that she learns that the parent behind most of the challenges (Mrs. Spencer) checked out Blume's work multiple times when she was a student at Shelbourne Elementary. Amy Anne "outs" Mrs. Spencer, which, let's face it, she kind of deserved. However, Mrs. Jones does take the opportunity to explain to Amy Anne about patron privacy.