A number of men who have previously been acquitted of serious crimes are found dead. A card with the word Spies has been pinned to the chest of each of them. Steed and Mrs Peel are given the task of discovering who has been carrying out these crimes and why. Mrs Peel realises that each of the dead men had been involved in some kind of controversy and suggests that they keep an eye on Ralph Latham who has recently been under suspicion of involuntary manslaughter.
The pair keep a careful eye on Latham for several days, but nothing happens to the businessman. In the meantime, Sam Cobley is accosted by a pair of men, one of whom states that Cobley is responsible for two suicides due to his fraudulent activities. He insists that he was found innocent of all the charges brought before him and fights back. The two men scarper.
Steed is contacted by an anonymous man who tells him of the attack on Cobley. Cobley has recognised one of his attackers as Vic Lester, a former detective at Scotland Yard, who left the police force after being accused of brutality. Steed rendezvous with Mrs Peel, who is still observing Ralph Latham, and tells her the latest news. He suggests that they continue to watch Latham, as the attackers are likely to hold off Cobley for the time being.
A few nights later, Mrs Peel sees Rick Lawson, a private detective enter Lathams house. Mrs Peel thinks that Latham must have wind of something and is hiring himself some bodyguard. Steed seems to think that something much more suspicious is occurring and, using a skeleton key, he enters the house with Mrs Peel. Inside they confront two gunmen one of whom is Lawson and after a struggle in which the two escape Steed finds Latham dead in the bath. He has been shot.
In their haste to escape the two gunmen have dropped a Spies sign, two Dewsbury bus tickets and a shoe repair ticket, also from Dewsbury. Steed makes some enquiries at Scotland Yard. He discovers that Lawson was also a former police officer who had been dismissed for brutality. The other man is Carver, a former CID man who had been involved in Lawsons activities and had quit at the same time. Steed speaks to Brian in Records, who tells him that just outside Dewsbury lives ex-judge Corder, who resigned from the bench when a death sentence he had passed some years earlier was quashed by the High Court.
The Avengers head off to Dewsbury (an unusually northerly destination for The Avengers, but when they get there it does look suspiciously like every other town or village in Avengerland). Stopping only to sample the veal and ham pie at The Evening Star public house, they head for Judge Corders house. Steed calls at the front door while Emma waits in the grounds as back-up.
Steed tells the man who comes to the door that he is a reporter from The Globe newspaper who is preparing a story called Justice Today and Yesterday. Steed thinks he recognises the man as disbarred barrister, Mark Lear. Lear takes Steeds bowler, and he is allowed in to see Judge Corder. Corder explains his controversial theory to Steed the Death Penalty for all enemies of society. They are interrupted by Lear, who tells the Judge that Mr Dison has a query in the library. Steed takes this opportunity to contact Mrs Peel via his tiny two-way transistor radio. He alerts her to the possibility of action soon.
Judge Corder returns and asks Steed why a reporter would wear a steel-lined bowler hat. Steed tells him its for protection against the criminals he encounters in his daily work. The judge doesnt believe him and calls for a trial in the library Steeds crime, obstructing Spies and thus, in the Judges twisted logic, obstructing justice. At the trial, Steed is found guilty of obstructing SPIES The Society For Punishment of Immune Enemies of Society and sentenced to death. Mrs Peel emerges from the shadows and, as she is rushed, shoots one of the criminals dead. Steed knocks out Lear then tackles the judge. The Avengers are triumphant justice is saved.
Observation With some extensive rewriting this could have been the premise for a season four story corruption and skulduggery in another great British institution the law. The ex-policemen and Scotland Yard would have had to be written out of the story, but at least there are no uniformed officers on view.