Devolution: A Firsthand Account of the Rainier Sasquatch Massacre is a 2020 epistolary horror novel by Max Brooks (author of World War Z). It is framed as an investigation, pieced together from a recovered journal, interviews, transcripts and other documents, into the fate of Greenloop — a small, tech-dependent eco-community in the Cascade foothills.
When Mount Rainier erupts, Greenloop's high-speed internet and solar-powered comforts are no help: the eruption strands its residents, and displaced, food-starved Sasquatch turn to the settlement as prey. Cut off, unarmed and unprepared, the community must confront both the collapsing infrastructure of modern life and a predator that should not exist.
As with World War Z, Brooks builds the horror from testimony and documentary fragments rather than straight narration, using the format to interrogate how ill-suited comfortable modern life is for genuine crisis.