Skyla has lived secretly within the city walls of Bollingbrook for eleven years, playing among the airship factories and trainyards. As one of the Gutter District's nameless destitute, it has gone undiscovered that she has a unique talent: when Skyla looks at a person's shadow she sees through it and into another world. She can see people's fears, desires, their past sins - all as swimming, living creatures.Her mother has never told her the real reasons why they must remain hidden, never explained the true dangers that exist outside the city walls. But when her mother's past catches up with them both, Skyla finds she must flee out of the city and into a world still recovering from a second Dark Age, a world of adults with secrets only she can see.For a stranger has recently moved into Bollingbrook, a man some call the Pope of the South, a witch hunter to some and a hero to others. When more children begin to disappear, suspicions are raised and an unlikely search party is formed to find Skyla in the hopes that they aren't already too late.