It's beginning to feel a lot like tourist season in Sea Harbor, Massachusetts, and beachside shopkeepers are getting ready for the annual wave of visitors. But even before the season starts, the heat is on to find a killer . . . The Yarn Studio's Seaside Knitters have their hands full designing new classes for vacationers, as well as testing each other's originality by creating a single blanket together. Birdie's teenage granddaughter...