"48-year-old Nantucketer Dabney Kimball Beech has always had a gift for matchmaking. Some call her ability mystical, while others - like her husband, celebrated economist John Boxmiller Beech, and her daughter, Agnes, who is clearly engaged to the wrong man - call it meddlesome, but there's no arguing with her results: With 42 happy couples to her credit and all of them still together, Dabney has never been wrong about romance. Never, that is, except...