Sinister Barrier by Eric Frank Russell (1939; revised 1948): Probably the first science-fiction novel to be based on Charles Fort’s pseudo-scientific speculations that human beings are the property of something alien, and Sinister Barrier is not shy about its influences — there are pages of direct quotes from Fort’s work, excerpts which consist mainly of quotes from various newspapers and what-have-you about unexplained phenomena. Specifically, Russell uses Fortean clips about flying energy balls (!!!) and mysterious disappearances to concoct a tale of flying energy balls that occasionally make people disappear.
Well, OK, there’s more to the novel than that. And it’s set in the then-far-flung future of 2015, when humanity has developed gyrocars and video-telephones but not television. Hunh?
Anyway, leading scientists start dropping dead from either heart attacks or suicide. A hyper-intelligent government investigator tries to find out why. They were experimenting with a drug combination (which included mescaline and methylene blue!). It caused the human eye to be able to see more of the visual spectrum. And what they saw killed them!
Enjoyable, fast-paced, and paranoid fun in its first half, the novel drags a bit when humanity launches its attack on the things that it couldn’t previously see. Invisible balls of energy have been feeding on humanity’s emotions for millennia. There’s certainly more than a whiff of such later paranoid classics as They Live here, though both horror and social commentary are soon replaced by the mechanics of the science-fiction thriller. And several pages of quotes from Charles Fort. In any case, a lot of fun, and something Hollywood should look into adapting. It would make a great movie. Recommended.