A mysterious hunched masked character known as The Fiend is killing theatre people using that well known Golden Age method of frozen bullets. Reporter Jean Monroe (June Collyer) is on the Fiend's hitlist after she lies she knows what he looks like and narrowly avoids death. Now with her friend/colleague Frank Gordon (Lloyd Hughes) she looks to find out just who this Fiend is...
The police are investigating too of course but bring in stage writer / part-time amateur detective Peter Fortune (Lawrence Gray) to assist. He suggests an associate who is an expert in devising fiendish ways to kill people. Soon an actor called Reardon (Jack Mulhall) is arrested as the Fiend but is he the guilty man? Well no as he ends up dead too...
So this looks like a pretty standard Golden Age type mystery. Indeed there is nothing that novel about the film, the mystery takes second place to much running around but it's an entertaining romp. The real identity of The Fiend is pretty obvious to be honest but it's fun following the case.