This is a great early Biograph Company action adventure film. It matches up well with the D.W. Griffith, "A Girl and Her Trust" which came out the same year.
Mabel seems to be working ironing dresses in a dress shop when something catches her attention in a newspaper. Apparently, it is an ad on becoming a detective. Mabel goes rushing off to a Detective school run by Fred Ward.
Apparently, the school is something of a shame, as Ward just gives her a badge, a gun, and a fake mustache. It doesn't matter because Mabel is on the case. She almost immediately runs into a suspicious looking character and follows him. She carefully notes the secret sign he uses to get into a suspicious looking house - knock four time, wait a moment and knock a fifth time. There is also a secret sign to enter - the finger moves down from forehead to chin, then across the throat, as if someone was cutting a throat. Mabel sees from the window that the clubhouse is an anarchist society and the man she followed has prepared a bomb.
Mabel goes home and puts on men's clothing. Besides being an early, if not the first female detective movie, this is also an early example of cross-dressing. She looks rather boyish in the tight fighting men's suit and then she puts on her detective mustache.
Mabel gives the secret knock and secret sign and manages entrance into the anarchist club house. However she is unable to capture the gang. Instead they imprison her. Thinking quickly, Mabel grabs a chair, smashes a window and escapes.
She goes to her teacher Fred Ward for help. He comes with her, but ends up following the wrong man. Ward mistakes a fruit melon that the man is carrying for a bomb. Ward finds three cops. This might be the earliest incarnation of the Keystone Cops. They follow Ward back to the melon man's apartment, but when they find out it is only a melon, they arrest Ward. In the meantime, our Ketchem Kate has tracked down the real bomb-throwing anarchist.
I won't give away the ending, except to say that it is entirely satisfying.
For fans of movie Female detectives, comical cross-dressing, or Keystone Cops, this movie is a must.
