Rose lives in New York, the city of bright lights and excitement-where extraordinary things happen every day. But Rose wasn't born in New York; she was adopted and arrived there at age two; and though Rose loves her home and her adopted family, sometimes she can't help but feel different, like she's meant to be somewhere else.

Then one day in Central Park, Rose sees something truly extraordinary: a crystal staircase rising out of the lake, and two small figures climbing the shimmering steps before vanishing like a mirage. Only it isn't a mirage. Rose is being watched-by representatives of U Nork, a hidden city far more spectacular than its sister city, New York. In U Nork, 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.

And then she learns the most astonishing thing about U Nork: its citizens are in danger, and only Rose can help them.

In this masterful new fantasy, best-selling author Adam Gopnik joins with legendary illustrator Bruce McCall to explore powerful themes of identity and the meaning of home.