Who but Basil of Baker Street, Sherlock Holmes of the Mouse World, could solve the Case of the Counterfeit Cheese in a few hours, and sail at midnight for Mexico on a secret mission?

There the theft of the Mousa Lisa, which has baffled Mexican policemice for months, challenges all his skill as a detective. Then his good friend, Dr. Dawson disappears! Is this the work of the ruthless Professor Ratigan, Crown Prince of Crime?

Featured in this fourth book about Basil and the Panadero Street Irregulars—seven young Mexican mice. Disguises, surprises, steadily mounting suspense, and even a liberated female mouse make this a mystery to delight all Basil fans, from ages eight to eighty!

From the dust jacket