A whodunnit mystery story in which the detective protagonist comes to the wrong conclusion about who the culprit is, but the reader is given enough information to be able to figure out the correct answer.
An ultra-wealthy family seals themselves in a fortified underground bunker, thinking that the fall of civilization is imminent. They suffer from a variety of structural, technical, and psychological problems. Slowly starving and going mad in the dark, they eventually kill each other. Meanwhile, the world above ground is totally normal.
Exposure to the internet having physical and psychological effects, much like radiation or toxic waste. The more intense and prolonged the exposure, the more severe the effects.