Dublin, 1816. A young nursemaid conceals a pregnancy and then murders her new-born in the home of the Neshams, a prominent family in a radical Christian sect known as the Brethren. Rumours swirl about the identity of the child's father, but before an inquest can be held, the maid is found dead after an apparent suicide. When Abigail Lawless, the eighteen-year-old daughter of the coroner, by chance discovers a message from the maid's seducer, she sets out to discover the truth. It's the year without a summer. A climatic event has brought frost to mid-July, hunger and unrest, and a lingering fog casts a pall over the city. An only child, Abigail has been raised amid the books and instruments of her father's grim profession, and he in turn indulges her curious and critical mind. Now she must push against the restrictions society places on a girl her age to pursue an increasingly dangerous investigation. Two groups have come to dominate the city: the Brethren, founded by Mr Darby, a charismatic preacher and evangelical, and opposed to them, a burgeoning rationalist community led by the Royal Astronomer, Professor Reeves.
Abigail's searches begin to uncover the well-guarded secrets of both factions, drawing the attention of a sinister figure who emerges in fleeting glimpses and second-hand reports: the man with the lazy eye. Abigail leads us through dissection rooms and hospital wards, austere churches and graceful salons, and to the equatorial room of the Saggart Observatory; and we see her interact with a wide assortment of characters: the family and staff of her Rutland Square home; her friends, peers and rivals; zealots, both religious and rationalist, while always shadowed by a seemingly pitiless sociopath, whom she believes has killed twice already, and will no doubt kill again ...Determined, resourceful and intuitive, and more than just a dutiful daughter or society debutant, Abigail Lawless emerges as a young lady sleuth operating at the dawn of forensic science.