Someone has stolen a page from a rare book in the New York Public Library. At least, that’s what Devlin’s friend Liza thinks she’s seen, but she can’t be sure. Any other kid might not see a crime here, but Devlin Quick is courageous and confident, and she knows she has to bring this man to justice—even if it means breathlessly racing around the city to collect evidence. But who is this thief? And what could the page—an old map—possibly lead to? With her wits, persistence, and the help of New York City’s finest (and, okay, a little bit of help from her police commissioner mother, too), Dev and her friends piece the clues together to uncover a mystery that’s bigger than anyone expected—and more fun, too.