One summer, Harold Parkette is in need of a new lawn mowing service. The summer before, a neighbor's cat was accidentally killed when another neighbor's dog chased it under the mower. Harold has been putting off hiring new help for the summer, but when he sees an ad for a mowing service he calls. A van reading "Pastoral Greenery" soon pulls up to Parkette's home. The man working for the service, a hairy, pot-bellied individual, is shown the overgrown back lawn and is hired. Harold is enjoying a rest as he reads the paper, wondering about the lawnmower man mentioning Circe, when he hears the lawnmower outside. Startled, he races to the back porch and sees the lawnmower running by itself and the naked lawnmower man following it on all fours and eating the grass. The lawnmower seemingly deliberately chases and kills a mole and Harold faints.
When Harold revives, the lawnmower man explains that this new method, introduced by his boss, grants substantial benefits, and that he makes sacrificial victims of customers who cannot appreciate the process. Parkette, though unnerved, allows the lawnmower man to return to work. As soon as the man is out of sight, Harold desperately calls the police, but is interrupted by the lawnmower man, who reveals his boss's name: Pan. The lawnmower briefly chases Harold through his living room before brutally slaughtering him.
When the police arrive, they conclude that Parkette was murdered and dismembered by a schizophrenic sex maniac. As they leave, the scent of freshly cut grass hangs strongly in the air.
The story was adapted in graphic form in Bizarre Adventures #29 (December 1981). The adaptation features the original text of the short story, accompanied by art by Walt Simonson. Publisher IDW rereleased the story in a portfolio edition shot from the original art in 2014.
A feature film, The Lawnmower Man, starring Jeff Fahey and Pierce Brosnan, was released in 1992 by New Line Cinema. This film used an original screenplay, borrowing only the title of the short story. The film concerns a scientist, Dr. Lawrence Angelo (Brosnan), who subjects mentally retarded Jobe Smith (Fahey) to virtual reality experiments. Jobe's mental abilities improve to superhuman levels as the process continues, but he lacks the emotional maturity and character to use his powers humanely. When Angelo's employers interfere with the process, Jobe becomes a homicidal megalomaniac. King won a lawsuit to have his name removed from the credits, and then won further damages when his name was included in the home video release. A video game adaptation, loosely based on the film, was released for the Super Nintendo, Sega CD, PC CD-ROM and Game Boy. A sequel film, The Lawnmower Man 2: Beyond Cyberspace, was released in 1996.