Writers often live in their own private worlds-sometimes realms of booze, deadlines and nerves. David Koepp's "Secret Window," the latest of innumerable movies adapted from Stephen King works, is about just such a world and how it quickly turns into a private hell.

In the movie-a clever, tense thriller that loses steam toward the end-Johnny Depp plays a King-style suspense writer named Mort Rainey, a hard-drinking recluse suffering from the pain of divorce and the torture of writer's block.

But Rainey soon has to cope with something much worse: the sudden appearance of a strange, crazy-acting dairy farmer from Mississippi named John Shooter (John Turturro), who pops up at Mort's secluded woodland upstate New York home, oozing malice.

Shooter, played by Turturro with all the homespun menace he can muster, is an amateur writer who claims that Mort stole one of his stories, "Secret Window," from him. Eyes glistening, voice a dour rasp, Shooter demands that, within three days, the author either prove he actually did write the story first, or somehow "make things right."

That should be easy. Shooter's story was written, he says, in 1997 and Mort recalls first publishing "Secret Window" in "Ellery Queen's Mystery Magazine" in 1994. But, dismissive of his scruffy accuser, Mort doesn't immediately retrieve the magazine-though he does hire a no-nonsense New York City detective, Ken Karsch (Charles S. Dutton), to keep an eye on things.

Soon, though, Mort's house is broken into. His dog is killed. And the house of Mort's estranged wife, Amy (Maria Bello), and her obnoxious new lover Ted Milner (Timothy Hutton) is burned down-the place where Mort had a copy of EQMM. As the threat grows, Mort's lack of control grows too. A writer used to living alone and creating murderous fantasies, he now faces real-life terror and a seemingly unstoppable assailant.

"Secret Window" is typical King primal horror stuff, another tale of a writer descending into darkness, bedeviled both by the outer and inner world. It's reminiscent of "Misery" and "The Shining"-though the source, "Secret Window, Secret Garden," originally a novella, is more stripped down.

That should be to the good. Koepp is a thriller specialist with a real affinity for this material. But though he's also one of the most successful Hollywood screenwriters of the last decade (scripting "Jurassic Park, "Spider-Man," "Mission Impossible" and "Panic Room" for other directors and "A Stir of Echoes" for himself), there's something awry in the movie's construction.

The early parts of this well-cast, well-produced movie spin by with almost effortless smoothness. Depp plays effortlessly too. With his usual tongue-in-cheek, offhand grace, he's an actor wonderfully adept at taking the audience into his confidence. Here, he doesn't so much act Mort's suffering as the writer's glib attempts to avoid suffering.

Depp is also ably backed by Turturro and by Bello as the retreating Amy, Dutton as the case-hardened Karsch, Hutton as unsympathetic Ted and Len Cariou as the town's over-casual sheriff. Each helps contribute to the gathering terror-part of which comes from the way we see can Shooter's attacks, symbolically, as a kind of spooky punishment or evil wish fulfillment. The double level makes "Secret Window" akin to classic novel/movie thrillers like "Strangers on a Train," and Mort and Shooter almost archetypal bonded antagonists.

That's why the last third of "Secret Window" struck me as disappointing and the last scene something less than the shivery climax Koepp wants. The climax is telegraphed too soon; after a certain point, one just waits for it, without bated breath. And even if you don't guess the ending, there's something too callous and dark about the very last scene.

Alfred Hitchcock always said that suspense is preferable to surprise, but in this story, the surprise is integral to the suspense. Koepp, an often ingenious writer, should have followed King's example and covered his tracks better. If he had, "Secret Window" might have been as good as "Stir of Echoes," and not simply a mini "Misery" and a not-quite "Shining."