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The Mad Gasser of Mattoon
An uncanny column about folklore and tabletop RPGs
You wake to strange sounds in your home. Moving carefully, you leave your bedroom to investigate. In the next room, you see blue mist swirling across the floor. Nausea brings you to your knees. You collapse. You cannot move, and a figure watches from your open window.
In real life, the Mad Gasser might just have been mass hysteria. In your world, he can be something much, much worse.
In the late summer of 1944, the small town of Mattoon, Illinois would come under attack from an elusive phantom. For two weeks, the town was plagued by a figure that would become known as the “Mad Gasser of Mattoon”, the "Anesthetic Prowler," and the "Phantom Anesthetist”.
This mysterious prowler stalked Mattoon at night, spraying a paralysing gas into the windows of unsuspecting residents. Starting on August 31st, more than two dozen cases were reported, in addition to many more sightings of a lurking figure. Detecting a strange odour in one’s house preluded the physical effects of the gas:
“Victims report that the first symptom is an electric shock which passes completely through the body. Later nausea develops, followed by partial paralysis. They also suffer burned mouths and throats and their faces become swollen.” (Nearby Decatur’s Herald, 8 September 1944)
Luckily, no one died or suffered serious medical consequences from the gas. Less lucky was the shortage of physical evidence, which included a white cloth, a skeleton key, and an empty tube of lipstick, but no real suspect. Burglary was a presumed motive, especially early on, but with no suspect that was only ever speculation.
Two weeks after the attacks began, the phantom prowler disappeared, never to be seen again.
The Mad Gasser’s physical depictions are usually based on the first case reported to the media. The Kearney family described him as a tall, thin man dressed in dark clothing and a tight cap. He allegedly wielded a flit gun; normally used to spray pesticide, it’s from this tool that he expelled his gas.
This gives us a general description, though another report describes the Gasser as a woman disguised as a man. Plus, if the victims were under the influence of a poisonous gas, we can’t rely on their descriptions to be completely accurate. In theory, the Mad Gasser could be anybody.
At first, the Mattoon police took the Gasser seriously. In the week following the initial attacks, however, the police were inundated with so many false cases that they diagnosed many of the victims as suffering from mass hysteria. Later, they solved the mystery by simply deciding that there were no victims at all. Everyone was suffering from mass hysteria, the news reports were stoking public fear, and the local women were anxious because the men were away in the war. This would become the accepted theory, and the Mad Gasser would go on to become a famous case of mass hysteria.
But was it?
Some at the time speculated the ‘gas’ was actually toxic waste or pollutants. Others have since argued that there really was an assailant mixed in with the false reports. There were multiple potential attacks on August 31st and September 1st after all, before talk of the Gasser reached the media on September 2nd. No attacks were reported in the two high-income areas of town either, and ceased incredibly abruptly for a shared delusion. There’s a legitimate argument to be made that the initial cases were true, but media reporting and hysteria lead to later false reports muddying the waters.
And, of course, there’s always someone who floats the idea that the Gasser was real—just not human.
Using the Mad Gasser in Your Game
The story of the Mad Gasser raises many questions. Is it a cautionary tale about mass hysteria? Is it a reminder that dismissing what people tell us is just the easy way out? Both make for an interesting discussion, but instead we’re going to be a bit crasser and ask: how can you use this story as inspiration in your own games?
The simplest way to use the Mad Gasser is as a villain. In your modern or period game, he can be a real person who has taken to testing out strange gasses on innocent people for his own nefarious purposes. What does the gas do, and what is he planning to use it for when he perfects it? Your PCs better find out before it’s too late—especially now the police have given up! The idea that the Gasser was a mad scientist was even floated at the time, so you’ve got historicity on your side!
Alternatively, you could lean into the more mythical status the ‘Phantom Anesthetist’ sometimes takes on. Here he’s an inhuman threat, a literal phantom. It explains why he was impossible to catch and suggests that the gas could be a supernatural fog that spreads in his presence. So what does this spectre want? Can the PCs put him to rest before his poisonous nature accidentally, or intentionally, kills someone?
An increasingly common idea in modern folklore is the idea that believing in something makes it real, usually adapted from the Theosophic thoughtform. So perhaps the Mad Gasser is both real and unreal, a monster summoned by a fear of it existing. This could be as simple as a case of mass hysteria manifesting a monster after the fact, or you could instead play with the idea of people creating thoughtforms as hostile action.
If you like the sound of the latter idea, you might want to check out how it’s explored in Pelgrane Press’ The Esoterrorists. In it, ‘esoterrorists’ summon horrific monsters into our world by convincing people they exist and psychically breaking down the fabric of reality.
So in the spirit of that game’s premise, here’s a monster pitch for the Mad Gasser as an alien creature summoned to our dimension by convincing people it simultaneously does and does not exist. I’ve written the statistics up for The Esoterrorists' GUMSHOE system, but the monster itself should be easy to adapt to any horror game!
The Phantom Gasser (GUMSHOE)
The phantom gasser is an extra-dimensional creature that hides in the intersection of belief and disbelief. Phantoms are tall, thin humanoids with skin fashioned from dark plastic. Their heads resemble old-fashioned gas masks, each individualised to a specific phantom. The phantom is hollow, filled entirely with poisonous gasses that it can release from its fingertips—one that can paralyse, another that induces hallucinations.
To summon a phantom, a hostile actor must create an environment of fear and confusion, of threat but disbelief. This is typically accomplished by a spate of violent attacks while dressed as a phantom in a community where local law enforcement can be convinced the danger isn’t real. When the fear of a possibly-inhuman attacker combines with a true lack of belief by others, a phantom can manifest in our world.
In our reality, phantoms feed parasitically. They infect victims with their hallucinogenic gas, often after first paralysing them so they cannot escape. While the victim is poisoned, their mind conjures personalised, hostile hallucinations that can physically interact with them. These hallucinations typically start with bullying and scare tactics, before escalating to physical harm and murder. Since no one else can see a victim’s specific hallucinations, no one can intervene. The longer the victim suffers, the greater the release of psychic energy upon their death for the phantom to feast on. Sometimes a phantom will dose a victim over several nights, escalating their waking nightmares until death might even feel like a release.
Ultimately, each victim’s death is different and inexplicable. They can appear as accidents, suicides, heart failure, and even murder. But there’s no real weapon, almost no physical evidence at all if one doesn’t know what to look for (markings on window sills, odd boot prints, trace elements in the victim’s blood). Given the difficulty of solving the crime, and that it occurs in an area with apathetic or hostile law enforcement, the phantom has an easy feeding ground.
Abilities: Athletics 8, Health 20, Infiltration 6, Shooting 12
Hit Threshold: 4
Alertness Modifier: +1
Stealth Modifier: +2
Weapon: Special (hallucinogenic gas, paralysing gas)
Armor: +1 vs. Shooting (when damaged by a piercing attack, hallucinogenic gas leaks into the surrounding area)
Gas: This creature contains a mixture of dangerous gasses inside itself. It can make Shooting tests to attack with either gas. Direct contact is automatically effective, while indirect contact (such as entering an area filled with gas) requires a Difficulty 4 Health test to avoid being affected.
▶ Hallucinogenic: Causes the victim to violently hallucinate for several hours. They can physically interact with these hallucinations, and vice versa. If someone can successfully convince the victim they are hallucinating, they may concentrate and make a Difficulty 4 Stability test to dispel the illusions.
▶ Paralysing: Induces a partial paralysis that increases the difficulty of all physical general ability tests by 1 for the next hour. This gas can be inflicted more than once, each time increasing the difficulty and hour duration by 1. Counteracting the gas requires a Difficulty 4 Medic test.
Feeding: Interacting with the hallucinations is likely to trigger multiple instances of potential Stability loss. When the phantom feeds on a freshly dead victim, it refreshes its pools by a number of points equal to the Stability the victim lost this way before they died.
And that’s it for the Mad Gasser of Mattoon!
Thanks for reading; I decided to do something a little different this week with a GUMSHOE monster, so I hope that wasn’t too off-putting! Most weeks I’ll still be looking at a fantasy creature with an old-school fantasy write-up, but if a particular game suits a piece of folklore really well I’m keen to shout it out! Regardless though, I hope I can always show that there’s always more than one way to use a piece of folklore or urban legend in your game!
Penny for your thoughts: Have you ever run or played in a game that played with the idea of whether an antagonist was even real?
~ A.C. Luke
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Clark, Jerome. 1993. Unexplained! 347 Strange Sightings, Incredible Occurrences, and Puzzling Physical Phenomena. Visible Ink Press: Detroit.
“Aesthetic Prowler" on the loose Mrs. Kearney and daughter first victims”. Daily Journal-Gazette (Mattoon). 1944-09-02. Archived from the original on 2007-09-27. Retrieved 20 August 2022.
Dash, Mike. 2000. Borderlands: The Ultimate Exploration of the Unknown. Overlook Press: New York.
Smith, Willy. “The Mad Gasser of Mattoon: Was the Famous Mass Hysteria Really a Mass Hoax?” Skeptic. Retrieved 20 August 2022.