New York City. 1897. Sara Howard has opened a pioneering private detective agency. She reunites with formidable alienist Dr. Laszlo Kreizler and New York Times journalist John Moore to find the kidnapped infant daughter of a Spanish dignitary.

All is not what it seems at the Lying-In Hospital as Sara persuades a young nurse to disclose what happens behind closed doors. Kreizler is convinced that hypnosis might unlock the traumatic memories of Senora Linares.

After the horrific murder of a Lying-In Hospital employee, the team are now hot on the heels of the murderer. Sara enlists the help of Joanna to tail their prime suspect. Sara, Kreizler and Moore try and put the pieces together.

While Sara, Moore and Kreizler struggle with decisions about their future paths, New York is in the grips of an all-out manhunt for the killer, and the team must overcome the wrath of the police and an underworld gang on the rampage.