When his friend Mirrin Stentrill exhibits her visionary paintings - monumental portraits of cats - the rodent township of Pinchester is outraged. The mayor wants to close down the show and militant mice threaten to do much worse. Then just when things are building to fever pitch, a mysterious old chipmunk announces his revolutionary new theory. He believes that a civilisation of cats ruled the world long before mice had even scuttled out of their caves! Could there be truth in such shocking horrors? There are those who would resort to anything to stop the world from finding out the unspeakable. To discover the truth our heroes must travel up the Longish River, across the Great Desert to an ancient tomb that lies buried deep in The Sands of Time.