Esperanto was a failed attempt at the turn of the last century to create a Universal language based on the commonalities of several major European and Latin-based languages. Several societies developed, and it was a nice, progressive idea, but only a few tens of thousands of people ever really spoke it (including billionaire financier George Soros).
And then, for some reason, The Outer Limits creator Leslie Stevens made a horror/sci-fi movie in 1965 called Incubus…which is entirely in Esperanto. A made-up foreign language certainly lends itself to horror and sci-fi. And William Shatner’s in it, who you’ll be happy to learn retains all of his Shatneresque pauses and acting quirks in another language.