Twelve-year-old Billy Pyke has a talent for sorting things out, whether it's his chaotic family home or the busy book stall at Paddy's Market. In 1871, the market is the loud, smelly, marvellous heart of Melbourne, and Billy is delighted to work at the book stall there for the eccentric Mr Cole. When his new friend Kezia warns him of a sinister magician called the Obscurosmith, Billy can't believe her stories of magical deals gone horribly wrong - until he sees them happening. And the night that the Obscurosmith crosses a terrifying and dangerous line, Billy realises something: if he wants the Obscurosmith stopped, he'll have to do it himself.