Addison Anderson is a clever, cheerful girl, who is currently studying the castles of other countries. Having won a creative writing contest, and a free trip to Canada, she is curious to meet her Canadian challenger. To Addison's surprise, her very own cousin, Corby Clemens, comes through the door! While the Andersons visit the Clemens' clan, Corby's cat, Clover, disappears! Addison and Corby find clues that point to a Cat Burglar, and Corby's concern for Clover convinces him to call in the Royal Canadian Mounted Police. Corby is confident that with them on the job, the Cat Burglar will soon be caught, or will he?