Book excerpt: In a masterful new fantasy evocative of Alice in Wonderland, New York Times bestselling author Adam Gopnik explores the powerful themes of identity and the meaning of home, with stunning illustrations from renowned New Yorker artist Bruce McCall. Ten-year-old Rose lives in New York, the city of bright lights and excitement, where extraordinary things happen every day on every block. But Rose wasn't born in New York; she was adopted as an infant from a far-away country. Rose loves her home and her family, but sometimes she can't help but feel like she doesn't belong. Then one day in Central Park, Rose sees something extraordinary: a crystal staircase rises out of the lake, and two small figures climb the shimmering steps before vanishing like a mirage. Only it's not a mirage. Rose is being watched - recruited - by representatives of U Nork, a hidden city where Dirigibles and Zeppelins skirt dazzling skyscrapers that would dwarf the Chrysler building. Impeccably dressed U Norkers glide along the sidewalks on roller skates. Rose can hardly take it all in. Then she learns the most astonishing thing about U Nork. Its citizens are in danger, and they need Rose's help, and hers alone…