On a dark evening in 1890, a murderer strikes in the middle of New York City’s Washington Square Park. Seemingly no one has seen the attack. Both the police investigators and private detective Joe Phenix are at a loss as to how they can proceed. However, Joe Phenix begins to get tips from a veiled woman who seems to have been mesmerized. The veteran detective doubts the powers of clairvoyance, mesmerism, and second sight, but his doubts are challenged as more mysterious revelations appear.