A mad scientist needs a human head for his mechanical man and sees the Stooges as perfect candidates.
Shemp fantasizes about the exciting life of a private eye, when a beautiful blonde in distress rushes in begging for help, claiming she is being followed. While the Stooges search the hallways, she quickly scribbles a note and is captured by a mysterious figure.
The stooges become detectives and go to the aid of girl in the clutches of a mad scientist. The boys arrive at a spooky mansion where the madman is building a mechanical man that needs a human head. After declining the opportunity to supply a stooge-head for the experiment, they find the girl and escape, only to wind up in a car driven by the headless robot.
While in the lab, the scientist tries to cut off Moe's head, but does not succeed. The Stooges runs throughout the house, trying to hide from the scientist and his butler.