1930, New York. In the unbearable heat of summer, Irish immigrant Will Carthy works as a riveter on the tallest skyscraper in the world, spending his days above the clouds and his nights fighting loneliness.
When his half-sister, Isobel, sails out to join him, Will hurries to meet her at Ellis Island, only to find that she seems to have vanished before passing through immigration control. And so begins Will's quest, scouring the teeming tenements for a red-haired girl who now haunts his dreams..