In 1718, sixteen-year-old Eliza Tally is in the passionate throes of first love, blinded to the folly of her actions when seduced by a young gentleman. Soon enough, Eliza is pregnant and without a proper marriage certificate. Acknowledging his responsibility but unwilling to meet his obligations, the young man negotiates with Eliza’s crafty mother: Eliza is sent in service to an apothecary in London until after the child is born.

London is at first overwhelming, Eliza whisked into her new home still covered with the dust of the road. Mr. Grayson Black, her employer, wears a black veil to disguise his features; his experiments questionable, Black’s laboratory is off limits to any save his wife. Under the supervision of the dour Mrs. Black, other than the apothecary’s apprentice, Edgar Pettigrew, there is only one other servant, the disfigured and mentally challenged Mary. An oppressive gloom pervades every day of Eliza’s service, the girl increasingly burdened by the hopelessness of her predicament.

Black is unquestionably evil, a true Jekyll and Hyde although his experiments are considered scientifically sound by the Royal Society, his intention to publish his and gain the renown he so craves. Eliza performs her duties, at first believing that Mr. Black will help her dispose of the unwanted child. Certainly such is not his intention, obsessed as he is with the effect of certain stimulations and fears upon an unborn baby. But Eliza has no way of knowing the extent of her employer’s machinations, her fears exacerbated in this monstrous place, her only companion the dim-witted, disfigured Mary.

The sense of impending menace grows with the child in her belly, her only ally the clumsy Mary, who attempts to communicate an unconditional friendship to the disdainful young woman. As her original antipathy toward Mary slowly becomes a grudging affection, Eliza realizes that there are more dangers afoot in Black’s household, her innate intelligence whispering, “run”.

Dodging the grasping hands of Edgar Pettigrew, Eliza has her baby only to lose it soon after. Rather than releasing her from this strange bondage, Eliza finds that the Blacks own her indefinitely, no relief in sight, save Mary’s patient ministrations. When even Mary becomes an object of Black’s vile interest, Eliza is desperate to find an avenue of escape.

Filled with danger and the inequities of class and circumstance, London is murky and sinister, Eliza’s few forays to a local French bookseller her only exposure to the city and its mysteries. Her imagination fueled by dread, Eliza realizes too late the extent of Black’s duplicity. Her one hope for salvation, a French bookseller, turns his back when she most needs help, a bright future plucked from her hands.

While London is awash with new ideas and inventions, the old superstitions still dominate medicine and science, an uneasy joining of past and future. One is left to consider the true nature of monsters, whether created by “scientific” experiments or in fact the victimizers who prey on the helpless. In this acute study of human nature, pride and greed, Clark once again mines the underbelly of London for her treasure: innocence, men and monsters.