Mr Keen gets a visit from a thug who he put into jail five years ago. He had vowed to get revenge on Mr Keen, but now he comes only to get information on the guy who squealed on him. Definitely a gruff thug who is a distasteful sort to Mr Keen.
After the man leaves, the newspaper headline announces the murder of the informant. Now Mr Keen has a young lady waiting for him to plead for help. Her husband has been picked up for the violent murder. Yet another thug.
Mr Keen agrees to investigate, but he warns the lady that if evidence proves her husband is indeed guilty, he will have to report that evidence even if it goes badly for her hubby.
Suddenly there are three thugs, all notorious for being ruthless killers in the past, being accused, but they all couldn’t have done it. Even known ruthless killers deserve a break, so Mr Keen has to sort through the details to pick the right one, unless he gets himself killed in the process.
As ruthless as the suspects in the case may be, Mr Keen puts forth his best efforts to look at the facts with a level head. Still, it seems that at every turn more killers pop out to challenge the elderly, mild mannered investigator.
He may not have the braun, or wise cracks of Boston Blackie, or George Valentine, but he still outsmarts his would be killers, just in time for the cops to pick up the reall mastermind behind this mess.
The good news is that at least one of the tough ghuys seems to go straight in the end.