When chimney sweep Tom Wasp is handed a pawn ticket by his friend Eliza Hogg on the day before she is due to be hanged in Newgate, both he and his apprentice Ned are mystified when the reclaimed item turns out to be a sailor doll. It is no ordinary doll, however. This one holds a secret that has the two most notorious gangs in London's East End, the Rat Mob and the Nichols, at each other's throats. When Dinah, the daughter of the leaders of the Rat Mob, is found murdered Tom resolves to find her killer. Helped by Ned and the self-appointed Bug Destroyer to Her Majesty, the redoubtable Mr Chuckwick, Tom pursues the trail.