Book 6 in this excellent historical series about a lady Pinkerton detective.

Fleeing her mother’s attempt at matchmaking, Pinkerton detective
Penelope Hamilton Wynch travels to a Connecticut hotel for a
straightforward assignment: escort her sister-in-law Flora to New York,
where she is to serve as a witness in a counterfeiting case. But
Flora—an understudy player in a production riddled with strange
accidents—is poised to assume the lead role and refuses to leave town.

Coaxing a reluctant witness is the least of Pen’s worries after a
knife-wielding intruder breaks into Flora’s suite in the dead of night.
Pen thwarts the attack—at the cost of her second-best shirtwaist, no
less—but the man escapes. Are the counterfeiters trying to silence
Flora? The lady in question remains stubbornly uncooperative.

With more questions than answers, and the growing suspicion that someone
in the hotel—possibly in the acting company—is working against them, Pen
turns to her trusty lockpicks and derringer, along with her good friend
Cassie, in a search for answers.

But probing secrets comes with a price…and the acting life can be just
as hazardous as detecting.