蒙娜丽鼠密码》内容为：一个偶然的机会，杰罗尼摩得到一个消息：博物馆珍藏的一幅由达·芬鼠创作的名画——《蒙娜丽鼠》，在被送往实验室进行X光检验时，发现它的画面中有什么东西隐，藏着。斯蒂顿家族决心揭开这个谜团。经过反复核实和实地调查，他们根据提示发现了每一条线索中暗藏着的信息，最后找到11个字母，并破解了这个谜团。最终他们在“唱歌石广场”发现了一个重大秘密……为此本杰明、菲、赖皮还有杰罗尼摩被授予了最崇高、威仪的奖章。Book Description
Geronimo Stilton, is a best-selling book series written by Geronimo Stilton. In the series, Geronimo Stilton is a fictional character, an Italian speaking mouse who lives in New Mouse City on The Island of Mice. A best-selling author, he works as a journalist for the fictional newspaper The Rodent's Gazette. He has a younger sister named Thea Stilton, a cousin named Trap Stilton, and favorite nephew, nine-year-old Benjamin Stilton. Geronimo is a nervous, mild-mannered mouse who would like nothing better than to live a quiet life, but he keeps getting involved in far-away adventures with Thea, Trap and Benjamin. The books are written as though they are autobiographical adventure stories.
Geronimo investigates the rumors of a secret hidden in Mouse City's most famous painting, the Mona Mousa, and follows a trail of clues which lead below the streets of New Mouse City.