Miley Judson sits in a bar; drunk and trying to light a cigarette. A stranger lights it for him and tells him to keep the matchbox. It advertises "The Hellgramite Method. Cure for the problem drinker." He stays and drinks for another five hours until the bar closes. Miley returns home to his wife and son: his wife is fed up and says she's leaving him.
Desperate, Miley goes to the home of Dr. Murrick, where he admits he has a drinking problem. While he's tired of all the trouble it gives him, Miley can't quit on his own. The doctor offers him a capsule to swallow but warns him there's no turning back. Miley says, "Things couldn't get much worse," and swallows it. The next morning, Miley's wife is unforgiving. He promises things will change but ends up at the bar again that night. However, matter how much he drinks, he can't get drunk.
Miley goes back to see Dr. Murrick, who explains that the capsule contained the larva of a Hellgramite tapeworm. He shows Miley a "not yet fully grown" Hellgramite preserved in a bottle, something like a foot-long scorpion. Murrick says the Hellgramite can only be starved into dormancy by abstaining from alcohol. But it will be awakened any time Miley drinks and it will grow stronger each time, eventually becoming strong enough to kill him.
Suffering the agony of withdrawal, Miley sends his wife and son away while he fights the bottle. He pours all the liquor in the house down the drain. The pain is excruciating and debilitating. He visits the doctor again and demands to know what right he had to inflict the Hellgramite on him. The doctor is indignant: his wife and children were mowed down by a drunk driver.
Miley goes home and lives through another course of pain, almost succumbing to the temptation of an airline bottle left in his luggage. Back at the bar, another problem drinker searches for the light. Miley lights him up and gives him a Hellgramite matchbox. He pays his overdue tab and leaves the bar... permanently.