The series focuses on the 20-something year old anti-hero Johnny C, also known as "NNY" (pronounced 'knee'). He is a deranged serial killer, mass murderer, and spree killer who interacts with various other characters, generally by murdering them. He elaborately kills anyone who even slightly irritates him, then drains their blood and paints one of the walls in his house with it. Johnny is also willing to murder "innocent" people who, in his twisted mind, deserve their fate for some reason or another. The number of Johnny’s victims is in the dozens, if not hundreds—or perhaps even thousands. Authorities are unable to capture Johnny and seem unaware of his existence, even though his crimes are often witnessed in public and reported by the few who manage to survive.

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Johnny Homicidal Maniac #4 comic book

Krik manages to free Tess before a monster breaks free from the wall and kills Dillon. Krik tells Tess how he ended up in Johnny's clutches. The monster runs amok in a room full of restrained victims. Tess and Krik run into the doughboys. Mr. Eff is angry about Johnny's accidental shooting while Psychodoughboy is overjoyed. The monster catches up and consumes the doughboys as Tess and Krik flee upstairs to find Johnny clinging to life. Krik stomps Johnny's skull until the wall monster breaks through the floor. Krik runs for the front door, but, as he crosses the threshold, one of the monster's tentacles cuts him in half, and he falls with the monster screaming into oblivion. Tess looks into the void and fades from existence. All that is left of the world is Johnny's corpse floating through space on a section of floorboards

When Johnny's soul arrives in Heaven, he meets St. Peter and God. Johnny is thoroughly dissatisfied with the way God has been running the universe and tells him so. A woman named Damned Elise gives Johnny a tour of heaven. Johnny starts a massive psychic battle when he discovers that the souls in Heaven have mental powers which includes the ability to explode people's heads. In Hell, Johnny meets Senor Diablo, who reveals that Johnny is a "flusher" or "waste lock", a creature chosen to concentrate the spiritual byproducts generated by humans into a specific object or point in space, in this case the wall in Johnny's house. As Johnny died, the wall unleashed the built-up negative energy, in the process destroying the universe, which was then restored. Johnny then finds out that Hell's torments are entirely self-inflicted by the trivialities with which people obsessed over in life—everything from commuting to cream cheese to lint. Johnny is resurrected and finds himself in his house, but with all of his voices gone, replaced by a talking "Bub's Burger boy" named Reverend Meat. Johnny is left unsure if he really died or if he experienced some kind of dream or hallucination. Later, Johnny stands in line at a 24/7 to buy a "Frooty Pop" when a robber bursts in and shoots the clerk.

Twisted, surreal comic by the creator of Invader Zim