Birdie McAdam, a ten-year-old orphan, is tougher than she looks. She's proud of her job as apprentice to Alfred the Bogler, a man who catches monsters for a living. Birdie lures the bogles out of their lairs with her sweet songs, and Alfred kills them before they kill her. On the mean streets of Victorian England, hunting bogles is actually less dangerous work than mudlarking for scraps along the vile river Thames. (See glossary!) Or so it seems—until the orphans of London start to disappear . . .