A Plague of Bogles (How to Catch a Bogle)

Jem Barbary spent most of his early life picking pockets for a wily old crook named Sarah Pickles—until she betrayed him. Now Jem wants revenge, but first he needs a new job. Luckily Alfred the bogler, the man who kills the child-eating monsters that hide in the shadows of Victorian London, needs a new apprentice. As more and more orphans disappear under mysterious circumstances, Alfred, Jem, and Birdie find themselves waging an underground war in a city where science clashes with superstition and monsters lurk in every alley.