A sweet, floral smell drifts into a bedroom on a hot September night in 1944. Minutes later, a woman cannot move her legs, her throat tightens, and her husband swears he sees a tall, thin figure in dark clothing outside the same window. No broken locks. Nothing stolen. No chemical residue. Just a town that suddenly has a name for its dread: the Phantom Anesthetist of Mattoon, later immortalised as the Mad Gasser of Mattoon.

Mattoon, Illinois, already strained by World War II anxiety and poison gas fears, turns scattered complaints into a single roaming villain. A damp cloth found near a porch looks like the first hard proof, until laboratory tests come back frustratingly clean. Reports still multiply: odd odors, nausea, dizziness, weakness, even claims of blue vapor and a buzzing sprayer device. Police search yards and question suspects while citizen posses cruise the streets with weapons, creating a new risk that has nothing to do with any phantom.

As national reporters arrive, the story flips from terror to spectacle and local officers start noticing the inconsistencies: varying smells, mixed symptoms, no common toxin, no clear route. When officials float an industrial solvent theory and newspapers cool their tone, the attacks fade almost overnight. Psychologist Donald M. Johnson later called it mass hysteria. Later writers prefer a collective anxiety attack. The lingering question remains: what if one real incident lit the match?