The Hook: High-altitude vampires that live in the ozone layer.
The Premise: They aren't humanoid; they are translucent, kite-like organisms that feed on the bio-luminescence and electrical impulses of the human nervous system. They don't bite necks; they "latch" onto a person's shadow.
The Conflict: During a record-breaking heatwave, the atmosphere thins, and these creatures descend into a major city. People begin losing their shadows. Without a shadow, a human loses the ability to feel pain or fear, leading to a society that is blissfully, violently self-destructing. The protagonist is a blind scientist who is the only one "invisible" to the predator