As I implied, this is an old-school indirect narrative, in that Roscoe doesn't drop us directly into the main story, but instead introduces his narrator as a character facing the skepticism of his hearers. In this case one McCord, an American engineer working in Haiti, tells his colleagues that the wreck of the Santa Maria can be found upriver, and then describes his personal encounter with Columbus himself. Back in 1913, when he was just starting out in Haiti, McCord met a Professor Upchurch, who wanted to go upriver to find the Santa Maria. Upchurch has a theory that Columbus died in Haiti, abandoned by his colleague/rival Martin Pinzon, who then delivered an impostor to be imprisoned in Spain and die the death assigned to Columbus by history. Upchurch, and Roscoe, have no romantic illusions about the great explorer.
The poor, meek Indians, they were harmless as pigeons, you know. They thought the white men had come from heaven, but they soon found out differently. My, yes! The Spanish didn't have any use for them and set about exterminating them most thoroughly. So thoroughly that there wasn't a handful left alive a hundred years later, and today they're extinct. The poor Indians were taken as slaves and their women were meek and good looking -- it isn't the chapter on Columbus they like to teach in public schools.
Thus Theodore Roscoe, revisionist. Moving on, Upchurch offers McCord $1,000 -- multiply that by something like twenty to get the value today -- to guide him upriver. Their trek is complicated by the reported presence in the jungle of a fugitive from the U.S., someone with the same theory about Columbus as Upchurch, but also convinced that the Santa Maria carried gold to be salvaged. Soon enough, this "Blackbeard" is on our protagonists' trail, which leads to strange places. At the end of the trail waits a "living mummy," the supposed last of the Arawack tribe -- the people doomed by their encounter with Columbus. "Your average Indian is about as wordy as his twin in front of a cigar store," McCord narrates, "but this fellow wasn't the ordinary five-cent brand. Not by a jugful! That blind mummy was the Grand Kleagle of storytellers, and he held us like flies in the moon-spun web of his yarn."
Guacanagri tells of the coming long ago of "two great sea birds [with] wings that shut out the sun, and shiny men on their backs to fold those wings." The shiny men kidnap the king's daughter and torture her for knowledge of gold, of which the Arawacks had none. Divine intervention drives the invaders to wander to their deaths in search of gold, but Guacanagri relates, in McCord's words, that "they had to keep going even after they were dead. Dead men must find graves, and those dead strangers couldn't find a cemetery."
For a professor, Upchurch is slow on the uptake. It's not until Guacanagri identifies the leader of the shiny men as "Don Cristoval" that the academic realizes that the "mummy" means Columbus and seems to be confirming his own hypothesis. McCord finds the whole thing hard to believe, but out of no where appears a man in a 15th century Spanish uniform.
"This Spaniard was from the day before yesterday," McCord narrates, "From just about five hundred years before!" The old boy bolts at the sight of our moderns, and a hysterical Upchurch leads McCord on a mad chase climaxing with their discovery of the Santa Maria, complete with crew, captive princess, and Admiral of the Ocean Sea. Implausibly moved by Guacanagri's tale of oppression, Upchurch goes berserk at what looks like a ghostly reenactment of Columbus's atrocities. Finally, McCord must confront the great man one-on-one, horrified at the thought of fighting someone already dead....
Could this be true? Of course not! It's all just a story -- but in the story, could it have happened as McCord says? I'll leave you with this link to find out for yourselves. "That Son of a Gun" is Roscoe in fine form, engaged in hard-boiled spookifying. It's a pretty sweeping adventure in 26 pages and gives some sense of the fun of pulp, even if you have to hold your nose at some racist lines, even as Roscoe takes what looks like today's "politically correct" line on Columbus. Just as he refuses to sugarcoat the Columbus story, so we should take Roscoe and his fellow pulpsters straight, the better to understand how they and their readers saw the world in their time.