What in gouda is happening to New Mouse City? Thea Stilton is missing and someone has been burglarizing the most popular shops! Are the two connected? Geronimo, the famouse editor-in-chief of The Rodent's Gazette, is on the case. But Sally Ratmousen, the owner of the Daily Rat newspaper, thinks Thea is the thief! Can Geronimo and his family find Thea and clear her name? Find out in this volume of GERONIMO STILTON REPORTER!