The jewelers of Muskrat City are in trouble. A thief has been stealing precious diamonds, and no one has caught a glimpse of the crook! Can the Heromice protect Duchess Marilyn Mousekovia and her precious gemstone during her visit to Muskrat City? And more importantly, will they catch the elusive Invisible Thief? Series Information Geronimo Stilton, editor of the most popular newspaper in New Mouse City, would rather write about adventures than actually get mixed up in them. But each book finds poor Geronimo on another mayhem-filled escapade, usually thanks to his hilarious family. Despite mistakes and mishaps, he always rises to the occasion, displaying considerable smarts and a surprising amount of courage. With predictable yet exciting plots and a mousy main character who triumphs in the end, this series gives kids confidence as chapter-book readers and as heroes of their own stories.From his original series to spinoffs such as The Kingdom of Fantasy and Cavemice, Geronimo's bestselling books feature full-color illustrations, surprising facts, and countless comical characters. Silly fonts highlight choice words and phrases on each page, helping readers understand how to use strong vocabulary.