Mercy Watson: Princess In Disguise"Halloween was made for carefree Mercy Watson." School Library Journal When the Watsons decide to zip their porcine wonder into a formfitting princess dress for Halloween complete with tiara they are certain that Mercy will be beautiful beyond compare. Mercy is equally certain she likes the sound of trick or treating and can picture piles of buttered toast already. As for the Lincoln Sisters next door, how could they know that their cat would lead