Thea Stilton and the Lost Letters is the twenty-first book in the spin-off series focusing on Thea Stilton, the adventurous and spirited sister of Geronimo. Thea and her five resourceful students, the Thea Sisters (Colette, Nicky, Pamela, Paulina, and Violet), travel to a new, exotic location to solve a thrilling mystery. In this adventure, the focus is on a collection of historical, potentially valuable letters that have mysteriously vanished, threatening to rewrite a piece of history or expose a secret. The Thea Sisters use their unique skills—from technology and photography to sports and history—to follow clues, decipher puzzles, and outwit the villains, racing against time to recover the precious documents before they fall into the wrong hands.
