Daphne is off to St Rita's, an exclusive girls' boarding school. It sounds awfully respectable and Daphne herself is awfully respectable too. She loves to read, and is delighted to be offered the chance to interview for Librarian's assistant's assistant immediately upon arrival. But it turns out nothing is quite what you'd expect at St Rita's - you can't trust a padlock if the fourth graders are around, the floor has holes from cannonballs, the smell in the dining room is disgustingly foul, and Daphne discovers the librarian doesn't really exist. But there is a librarian's assistant, Emily Lime. And she's really a crime-solving genius, who's looking for a new assistant of her own. And booksmart Daphne is just the girl for the job, because mystery and intrigue are about to strike St Rita's and Emily Lime is going to need all the help she can get...