El cuento del ratón Pérez, by Kristy Placido

In El cuento del ratón Pérez, readers are transported to 1890 Madrid, where a boy king embarks on an unexpected journey filled with magic, adventure, and discovery. Alfonso is not a typical boy—he is the king of Spain. But when his baby tooth falls out, he discovers that being a king doesn't mean he understands everything. Alfonso meets the legendary ratón Pérez, a professional tooth collector. Pérez explains that lost teeth are not just discarded—they are collected, stored in a magical library, and transformed into stories. Eager to help, Alfonso magically shrinks to mouse size and joins Pérez on a nighttime mission across the streets—and beneath them—in a secret tunnel system. As they travel to retrieve the tooth of a boy named Gilito, Alfonso sees parts of his kingdom he never imagined. He walks through dangerous streets, escapes a giant cat with the help of clever rat soldiers and a brave dog, and witnesses the humble home of Gilito, a boy who has very little. Deeply moved, Alfonso