Some days Nora Nolan thinks that she and her husband, Charlie, lead a charmed lifeexcept when theres a crisis at work, a leak in the roof at home, or a problem with their twins at college. And why not? New York City was once Noras dream destination, and her clannish dead-end block has become a safe harbor, a tranquil village amid the urban craziness. The owners watch one anothers children grow up. They use the same handyman. They trade gossip and...