FOUR PAST MIDNIGHT By Stephen King Viking. 763 pp. $22.95

REGULAR VISITORS to the world of Stephen King know that its horrors burst forth from the least likely places -- the four novellas in this omnibus find horror in a transcontinental night flight, a camera, a small-town library, and a quiet Maine summer town during the off-season. Some of the environs and themes in these stories are familiar; others are not. One is the penultimate Castle Rock story, a prequel to the forthcoming Needful Things. Another, King tells us, is the last of his tales "about writers and writing and the strange no man's land which exists between what's real and what's make-believe." Still another takes us to the midwestern American town of Junction City, Iowa, where King proves that his talents as a regionalist extend beyond Maine into Sherwood Anderson country.

King is above all a master storyteller, and these stories grab hold and will not let go. And, being tales of horror, they have their share of suspense, violence, monsters and eye-popping special effects. But what makes them special -- in the way the best of King's work and so little of the rest of modern horror fiction is special -- is the believable, often moving ways his characters react when confronted with the unknown.

When, for example, Sam Peebles loses two books that he borrowed from the Junction City Public Library and sweet-faced, white-haired librarian Ardelia Lortz dispatches the Library Police to get them back, the ensuing events shatter the bedrock of pragmatism and rationality on which Sam has built his life. His search for the missing books turns into a quest of selfhood that takes him into the soul of small-town America and ends in a battle royal with a protean creature akin to the monster in It, King's mega-novel of small-town evil.

And when, in "The Langoliers," a handful of passengers on an American Pride airlines "red-eye" flight from Los Angeles to Boston awaken half an hour after takeoff to find that somewhere between the Mojave Desert and the Great Divide their L1011 has taken a detour into the Twilight Zone, they must each cope with the shock of the inexplicable and then join in a community of sharing and sacrifice if they are to survive.

Not all of King's people are as well-equipped as Sam Peebles or the passengers on Flight 29 to deal with an incursion of the monstrous, In "Secret Window, Secret Garden," writer Morton Rainey comes to Tashmore Glen, Maine, to recuperate from his "eerily quick and quiet no-fault divorce" only to find himself face to face with every writer's nightmare: a charge of plagiarism. Weakened by depression, a severe writer's block and barely suppressed rage at his adulterous wife, Rainey is in no condition to deal with his accuser, let alone with the amazing strings of events that occur when he sets out to prove his innocence. In this story King interweaves character, theme and stunning plot reversals with far greater control than in his earlier, less successful novels about writers, "Misery" and "The Dark Half." OFTEN KING's most memorable characters are larger-than-life recreants whose lack of decency and compassion makes them sitting ducks for the supernatural. Reginald "Pop" Merrill, sole proprietor of the Emporium Galorium and featured player in the last of these novellas, stands out as the most irresistible of King's Dickensian grotesques. Sporting a twinkle in his eye, rimless spectacles, a vest and a corncob pipe, Pop seems just a crusty blend of "crackerbarrel philosopher and hometown Mr. Fixit." But behind this facade is a mean-spirited, duplicitous soul whose allegiance to the technological debris that fills his junk store is far stronger than to the Maine community where he lives. Pop represents the sick undersoul of Castle Rock and a thousand like towns and is a fitting companion for the Sun Dog that gives this story its title.

With the exception of this story, which suffers from the digressions and repetitions that have marred King's last few novels, the tales in Four Past Midnight are exceptionally well crafted. King shapes his material with the sure hand of a master woodworker, tossing off unexpected similes, deftly using dreams to reveal character, subtly planting clues to coming revelations, and skillfully managing the coincidences on which his stories often hinge. If, like me, you have loved King's work for years but were pretty disappointed in his last several novels, then you'll be delighted with Four Past Midnight, his best work since Pet Sematary.

As King notes in his ingratiating introduction, these stories share a preoccupation with time "and the corrosive effects it can have on the human heart." But they share with the rest of his work a deeper concern for basic values such as selflessness, honesty and friendship. Now, as the blood and chaos of their spectacular finales begin to fade from memory, what I am left with is the warmth of King's abiding faith in "that stubborn, intangible spark which carries life on in the face of the most dreadful reversals and ludicrous turns of fate." Michael A. Morrison, a professor of physics and adjunct professor of English at the University of Oklahoma, has written about horror fiction for more than a decade.