4 ideas
In the Bugey region of eastern France, people, animals, and objects begin to vanish or turn up displaced, and locals attribute it to mischievous spirits they call the Sarvants. The captives are examined, some fatally, before the survivors are recovered and the truth becomes public.
The atmosphere is treated as an ocean with humans living on its floor, like deep-sea fauna, while other creatures inhabit its upper layers. From above, our cities and fields become a seabed to be dredged. Our sense of standing at the top of the world depends only on where we happen to stand in a medium we cannot see through.
The same procedures humans use on animals, such as trapping, caging, measuring, dissecting, and cataloguing, are turned on humans by a more capable observer. Because the captor cannot read the specimen's inner life, human terror and intelligence register only as behavior to be recorded.
Faced with inexplicable disappearances, authorities, the press, and villagers each reach for the explanation their worldview already holds: criminals, hoaxers, or folklore spirits. Each partial theory absorbs the evidence well enough to delay the recognition of something genuinely new. This lets the invisible predation go on while people argue over the wrong suspects.