Bruce King is a radio engineer who while exploring the limits of the Ultra Short Wave band discovers that a device he has invented can create an area of complete darkness in a circle around him that projects up into the space and which can be seen for miles around, the area the circle of darkness takes in can be varied depending on how much power he gives his suitcase sized device. By flicking another switch on his “Black Zero Transmitter” he can also bring an even shorter short wave band into play making the column of darkness freezing cold.
Anyone one within his Black Zero, are blinded, including Bruce, until he also invents a pare of goggles that somehow allow him to be the only one able to see in his column of darkness and cold, though for some reason this also make things appear blue to him.
Deciding to fight crime with his invention Bruce dons a form fitting insolated blue uniform, and with a helmet and mask to hold his goggles, and becomes the King of Darkness.
The city he protects is soon baffled by the appearance from time to time of a pillar of pure black that they think is stabbing down from the sky, not knowing that it’s really Bruce driving in his car (when he has his mask on he can see well enough to drive) to fight crime.
The King of Darkness’s usual method of crime fighting is to look for a crime being committed with his device off, rush in on the criminals and turn it on blinding them, if they don’t surrender immediately, or even start to blast blindly away with their guns, his next move is to turn the Black Zero freezing cold until they pass out.
Bruce is helped in his fight against crime by Sgt. Burke of the city’s police department, who has been assigned the task of finding out who is behind the weird black column shooting around town leaving half frozen gangers and spies in it’s wake.
He finds this easy to do * by merely noting from miles away where the black pillar appears most often, which turns out to be Bruce King’s laboratory in his home.
Sgt. Burke however agrees with The King of Darkness’s methods and so instead calls him from time to time to give him advice and tell him where he can find criminals.
The King Of Darkness appeared in only three stories before disappearing into the darkness for the last time in 1941.
* Apparently both the Chief of Police and local newspaper reporters of this unnamed city are a bit on the dim side, as not only does Sgt. Burke find him by heading for the towering column of darkness, but so do a pair of reporters who decide it must be a new death ray, bursting in on King they ask him if he has a new death ray, to which he replies “No, now scram!” the next day the paper compliantly reports that “Doc King” has nothing to do with any death rays on it’s front page.