Stephen King loves a door stopper. Some of his classics (“The Stand” and “It,” for example) clock in well over a thousand pages.

But this old dog has learned some new tricks. Just in time for Halloween, the master of horror is releasing a delightful 146-page novel titled “Elevation.”

What the slim volume lacks in weight, it makes up in pathos. The book, which recalls Roald Dahl’s work for adults (down to its pen-drawn illustrations), follows Scott Carey, a Castle Rock resident, who can’t stop losing weight.

He eats like a “lumberjack;” he even carries hand weights when he weighs himself — no matter what he does, the scale’s numbers only go backwards.

What sounds like a dream to my ears, turns into a nightmare in King’s hands. No matter how much weight he loses, Carey still looks like a portly middle-aged man with a belly, even as he drops below 100 pounds.

“Sometimes I think this is the world’s greatest weight-loss program,” Carey tells his incredulous doctor.

Dr. Ellis responds: “Yes, but where does it end?”

Though “Elevation” echoes the King’s nastier “Thinner,” this book has a softer side. Carey’s goal is not to stall the inevitable or cure himself, but instead to find some meaning in his mysterious loss by forming an unlikely friendship with the ostracized lesbian couple next door.

As Carey’s weight approaches zero and his center of gravity shifts, the book lifts off to an unforgettable and deeply moving conclusion.