The Workings of a Clock

Tarrin is just a simple, honest girl. She is a tinker from The Black Market who steals and participates in illegal activities. Simple, Right? But her life was turned around when she was ratted out and then kidnapped by a mysterious group of rebels.Who travel on a train?

Tarrin's curiosity gets the better of her and she stays with the group, who seem to have quite a tragic backstory, what happened? And for the love of the gods, who is Tessa?