Sound the alarm

The League of Extraordinary gentlemen explored, through the medium of the graphic novel^[1], the notion of placing several contemporaneous fictional characters into a single, shared continuity.

Consider, then, the detective Sherlock Holmes. Consider the realm of fiction published, or set, in a period more or less concurrent with the gentleman's career. What adversary would test the great man's skills to their limits?

Perhaps something with tentacles, sir?

I find myself intrigued.

[1] and ONLY the graphic novel medium