"Suppose Some Daring Napoleon of Crime Should Hatch a Startling Conspiracy to Seize the Steamer, Intimidate the Crew and Passengers, and Possess Himself of the Huge Treasure?"

"The Mystery of the Thirty Millions."
By H. D. Umbstaetter (1851-1913), with Thomas F. Anderson (?-?).
First appearance: The Black Cat, April 1896.
Reprinted in The Red Hot Dollar and Other Stories from The Black Cat (1911).
Novelette (24 pages).
Online at Comic Book Plus (HERE) (select page 195 from the drop-down menu) and Archive.org (HERE).

". . . the Oklahoma was taking to the shores of insatiate John Bull the largest lump amount of gold ever shipped upon a single vessel within the memory of man."

Stealing a large sum of money from a ship well out to sea is a task not easily undertaken, and many would regard it a fool's errand, considering how few opportunities there are to effect an escape. The best course of action should be obvious: steal the ship . . .

Comment: A mashup of crime and science fiction that could easily have been expanded into a novel; the finale is a disappointment.

Resources:
- Other stories about thefts at sea that come immediately to mind include C. J. Cutcliffe Hyne's "The Looting of the Specie Room" (1900) (HERE) and Agatha Christie's "The Million-Dollar Bond Robbery" (1924) (HERE).
- FictionMags thumbnails our author, H. D. Umbstaetter, this way: "Born in Ohio; worked on newspapers in Cleveland, New York and Baltimore; became magazine publisher in Boston." From 1895-1912 he was the editor of The Black Cat magazine, where, mirabile dictu, "The Mystery of the Thirty Millions" was first published.
- The story makes a reference to "Colonel Sellers, of nineteenth century fame"; see (HERE), (HERE), and (HERE) for who "Colonel Sellers" was.

The bottom line: "If gold ruste, what shal iren do?"
— Chaucer