Lily Grim and The City of Undone

Lily Grim's life is a mystery. She has lived with her guardian Gabriel, in their rundown second-hand shop in the City of Undone, for as long as she can remember. For years, the city-dwellers have lived in uneasy discord with The Others - a community of wanderers forced to shelter within the city walls, after they were driven from their nomadic camps in the wilderness. But Undone is a dark and dangerous place to live, especially if you're an Other: feared for their special gifts, they are persecuted by the cruel Master of the City, and taken to the Ring - a prison from which few ever return.
When the Master captures Gabriel and throws him into the Ring, Lily is saved by a young Other boy called Dekka. He introduces her to a whole Otherworld that exists beneath the City of Undone. To her astonishment Lily discovers she is an Other, too - with powerful gifts - and is now in grave danger: because the Master wants her dead. But why?Can Lily find answers about who she is, and where she's from.
And can the new friends rescue Gabriel, before it's too late?