How can you stop a serial killer who has been dead for a hundred years?

The nail-biting new thriller in the #1 New York Times bestselling Agent Pendergast series. FBI Special Agent A.X.L. Pendergast always wants to protect his protegee Constance Greene from harm. But, against all odds, Constance has found a way to travel back in time to New York City in the late 1800s to embark on a dangerous quest: to stop the era's most infamous serial killer, Dr. Enoch Leng from bringing his plans to fruition. If she does, she can finally prevent the events that led to the shocking deaths of her sister and brother. Meanwhile, in present-day New York, Agent Pendergast is desperate to reunite with Constance before she gets stuck in the past forever... but can he find a way before it's too late?