Cosmo Jones, a correspondence-school detective from a small town, comes to the big city to offer his services to the police. He happens by where a gangster is killed by an opposing gang. Socialite Phyllis Blake is running around with gang member Tom and the opposing gang plan on kidnapping her. Cosmo is with Sergeant Flanagan when the attempt is made in front of a night club, where a bystander is seriously wounded in the gun-battle. Police Chief Murphy blames Flanagan for the shooting and demotes him. Cosmo, with the aid of a porter, Eustace and Flanagan's fiancée, Susan, tries to find the killer. Phyllis is finally kidnapped and Cosmo decides the act was committed by one of the two gangs. He has her father place an ad in the newspaper that contact has been made with the kidnappers. Each gang thinks the other is pulling a double cross, and one gang wipes out the other.
as Cosmo Jones
as Police Chief Murphy
as Susan Fleming
as Sgt. Pat Flanagan
as Eustace Smith
as Phyllis Blake
as Mr. James J. Blake
as Jake Pelotti
as Biff Garr
as Henchman 'Gimp'
as Police Commissioner Gould
as Mrs. Jake Pelotti
as Tony Sandol - Gangster
as Tommy Hayes - Informant (uncredited)
as Gangster
