Heike Lerner has a charmed life. a a a A stay-at-home mother married to a prominent psychiatrist, it's a far cry from thea damageda a child she used to be. But her world is a shaken when her four-year-old sona a befriends a little girl at a nearby lake, whoa vanishes under the water. a And when Heike dives in after her, there's no s