New York City. 1896. The heart of America’s Gilded Age. When a young boy prostitute is found butchered on the unfinished Williamsburg Bridge, an alienist named Laszlo Kreizler, a newspaper illustrator by the name of John Moore, a secretary, Sara Howard and a police commissioner named Theodore Roosevelt begin an investigation outside the law to find the serial killer.

Sara finds a clue and Kreizler tries to connect the evidence left behind by the serial killer. Kreizler takes Moore, Sara, Marcus and Lucius to Delmonico's in New York and informs them they're working together to catch the killer.

Innovative evidence leads the team to discover a crucial element in the case has gone missing. Kreizler and Moore interview a witness to find out what happened to Moore at the Brothel. Sara attempts to live in a world outside the investigation. Kreizler challenges them to look within themselves.

Kreizler and Sara discuss the capacity to kill. Moore goes on a date. Byrnes and Captain Connor keep an eye on a potential suspect. Roosevelt finds himself under public scrutiny.

The team learns more about the killer. Moore and Sara share an intimate moment. Kreizler seeks advice from an old mentor. Roosevelt takes action.

The team hatches a plan to catch the killer. Moore checks in on a friend. Kreizler faces his own self-doubt about the investigation. Roosevelt attends an event with the city’s elite. Sara looks into Kreizler’s past. Connor acts on impulse.

Kreizler and Moore follow a lead. Sara visits a hospital and is forced to confront her past. Cyrus, Kreizler’s carriage driver, recovers from his injuries. Byrnes and Connor plot against the team.

Kreizler and Moore travel to Washington D.C., Sara goes rogue in pursuit of the truth. Lucius tells Marcus a secret. Byrnes and Connor tighten their grip on the investigation.

Kreizler mourns the loss of a friend. Sara pushes the team to forge ahead. Moore warns his friend the killer will strike again. Cyrus seeks revenge.

Kreizler confronts the demons of his past. Moore tells Sara the truth. Connor takes matters into his own hands. The team closes in on the killer as time is running out.

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.

Sara uncovers a clue at the Siegel Cooper Department Store that leads her into dangerous territory. Moore struggles to balance his personal and professional life as he investigates a link to New York's criminal underworld.

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.

The clock is ticking for the team to locate baby Ana. Sara worries about her young undercover detective Bitsy Sussman. William Randolph Hearst hosts a lavish ball celebrating his goddaughter Violet's engagement to Moore.

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.

Sara and Moore return to the killer's abandoned house in search of new information about their suspect. Kreizler faces ruin after a tragic incident at the Institute. Sara and the team are enlisted to rescue another missing child.

Sara, Kreizler and Moore travel to Brooklyn in search of clues. Byrnes plans to double-cross the team as the killer's behavior becomes unhinged. Sara and Moore's feelings for each other force them to confront difficult choices.

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.