Eric Frank Russell’s 1939 Sinister Barrier is a standalone Fortean novel.
2015! The distant future! Bill Graham, a liaison officer handling relations between scientists and the U.S. Department of Special Finance, is alarmed at a recent wave of deaths amongst America’s top geniuses. Some died of what seems to be natural causes, others by suicide. Graham is convinced someone is murdering the USA’s brain trust.
Graham is on the right track but he does not grasp the scale of the crisis. The culprit isn’t the Soviets, the Asian Combine, or even some sort of sinister world-spanning conspiracy like Hydra, Thrush, Spectre, or the Phone Company, but something far more ominous. The target is not merely the United States of America. It is humanity as a whole.