19th century London: Hester Monk's voluntary work is increasingly demanding. Every night, she tends to women of the streets who have been injured or become ill as a result of their trade. Now a body has been discovered in one of the brothels. The dead man is none other than the respectable Nolan Baltimore, head of Baltimore and Sons, a successful railway company. Meanwhile Hester's husband, William, a private investigator, has been approached by Katrina Harcus, who suspects that the company her fiance works for may be guilty of fraud. That company is Baltimore and Sons. With the link between the two cases becoming ever clearer, Monk faces some staggering revelations.