Australian comic book The Invisible Avenger began publication with the January 1950 issue and lasted until August 1952, for a total of 28 issues. There are only three issues available at comicbookplus.com and this is the earliest and evidently the last to feature the title character. Starting with issue #12, the title changed to Invisible Avenger Comics and featured such heroes as The Blue Ghost, Secret Service Agent K-7, and Cometman. In the beginning, the comic book featured running stories to be continued in the next issue. It then moved to a single story per issue. Shortly before the title folded, it carried several stories, all about crime and criminals.
So who is The Invisible Avenger? I don't know.
There was a comic book character, Buzz Allen, The Invisible Avenger, who appeared in the first three (and perhaps only) issues of Hugo Gernsback's Superworld Comics (circa 1940), the creation of 23-year-old Charles Hornig, early science fiction fan and one-time editor of Gernsback's Wonder Stories. This is not The Invisible Avenger of the Australian comic books.
The Invisible Avenger is an unseen villain who threatens civilization. According to the first panel in this issue, he is an evil Chinese. (Shades of Fu Manchu!) Also in the first panel, a hero named Morgan put paid to the villain with a well-timed punch, leaving him to perish in flames. Evidently, in the previous issue The Invisible Avenger defeated five hundred robots belonging to Dr. Faustulus and infected Faustulus and Major Nollan with an unknown element which destroys human tissue. The two have only minutes left to live when Morgan attacks the baddie with a lucky punch. ("Take that - you rat!" says Morgan. "AWWWWW!" replies the defeated Invisible.)
Faustulus and Nollan don't die, although they are pretty sick. Faustulus has only three robots left and one of them -- SOMOS Number 330 -- flies to the burning building and rescues the three survivors. The trio are flown to another of Faustulus' creations -- a flying boat, "the strangest vessel ever built." (It goes 500 knots an hour and is crewed by the three remaining robots.) Soon the vessel goes zooming through the air with no stated destination, and travels for three days and two nights and then hits a cyclone. The storm knocks out the vessels controls. The lightning strikes and the vessel crashed into the ocean, taking Major Nollan and the three robots to a briny fate.
With no land in sight, Faustulus and Morgan hang onto a plank floating from the wreckage. Eventually they drift to a tropical island. where they hear native drums. ("There must be savages hereabout.") Natives there are and they are pygmies and they have spears. Taking the two captive, they lead them on a long trek to a staircase leading down to a large grotto, leading them to their hidden village. The main hut is decorated with thousands of skulls, leading Morgan to conclude that they are in the hands of cannibals.
Morgan and Faustulus try to escape but are soon captured and brought to the chief, a fat man with a large ring through his nose and a top hat. There's a huge totem in the center of the village with a door leading into it. The natives are scared of the totem and whatever is inside it.
The natives fatten our heroes up, furthering their belief that they are to be eaten. Another escape attempt and another capture. In the end the two are pushed into the giant totem, which has a staircase leading up to another door. The two get ready to open the door to their fate and...
What! Well the story must have been continued in the next issue, right? Wrong! Issue # 12 begins the adventures of Secret Service Agent K-7.
We never find out what happened to Faustus and Morgan, nor do we discover what the totem holds that is so terrifying. We have an ending of sorts, though. The last sentence in the story reads, "As Morgan and Dr. Faustulus await their fate, they glory in the fact that they have succeeded in breaking the power of The Invisible Avenger who was burned to death in his headquarters." (See panel one on the first page. I guess the rest of this issue was inconsequential. Ptah!)
Perhaps you can make more sense out of this than I did. Perhaps not.
Give it a try.