"If it's just a matter of aesthetics, it's not my job."

DAVID KOEPP IS A prolific screenwriter, and he's responding to my question about how he decides when to keep his mouth shut if he finds himself on the set of a film he is not directing. Though he's written screenplays for several big-budget Hollywood entertainments -- including the Jurassic Park films and, my personal Koepp favorite, Brian DePalma's operatic gangster flick, Carlito's Way -- in person Koepp comes off like a good-natured high school shop teacher. He's unassuming and plain spoken, and he really wants you to understand his craft.

"It has a lot going for it, screenwriting," he explains. "If you have some success, it pays very well. The hours are not terrible, because you can only write for so many hours in a day before your brain fries. You don't have to be on the set if you don't want to. However, you pay a price. For all those comforts, you also don't have control. It is not yours. You are, at best, assistant storyteller."

Koepp is squarely behind the storytelling controls on Stir of Echoes, his latest directorial effort (the last was 1996's interesting but shaggy Trigger Effect). Stir of Echoes stars Kevin Bacon as a working-class family man in Chicago who goes under hypnosis and awakens with frighteningly powerful psychic intuition. This new ability saddles Bacon with jolting images of violence, as well as haunting visitations from a mournful teenage girl who is also communicating with his young son. Koepp is clearly proud of the film, and when I mention that I like his work on the hypnosis bit, he lets me know that it was his favorite part, too.

"Sometimes you do a movie because there's a scene you want to be able to shoot. That was the one," he confesses. "I read it and I thought, if I can do this literally -- you know, just show exactly what he's asked to create in his mind -- it would be a chance to show hypnosis in a whole new light.... I thought, if I can show, in a weirdly objective way, what happens, and then pop out of it and we know nothing about what happens, just like the character... that's a hook."

It is a hook, and it's the best part of the film. When Bacon is put under by Illeana Douglas, he is mockingly dubious, deriding the whole idea of hypnosis. Slowly, though, he drifts off into the recesses of his mind and, in Koepp's slick bit of directorial illustration, we are privy to Bacon's physical constructions of Douglas' soothing words; he builds and rebuilds a mental image while we watch. When that image is interrupted by something darker, and when fish-out-of-water Bacon is tormented by post-hypnotic relapses, Koepp and his film have a creepy, Hitchcockian smoothness. There's a level-headed acceptance of genre that is one of Koepp's best attributes as a director: He simply wants to scare you.

Koepp loses the viewer, however, at the point at which the movie should truly be taking off. He has a good start with the story, which he adapted from a Richard Matheson novel. In updating Matheson's novel for the screen, Koepp has placed Stir of Echoes in a modern community that is threatening to fall apart, and he hints interestingly at the lurking undercurrent of violence and self-loathing that plagues not only the neighborhood but Bacon, too. But Koepp doesn't run with it, and once the setup is over, the film starts to crumble away into formula, allowing us to notice the gaps in its logic -- which is deadly in a genre piece. Unlike the superior The Sixth Sense, which it resembles (psychic child, restless ghosts, unwitting adults), Stir of Echoes doesn't twist itself into something surprising. You'll know halfway through what Koepp takes the entire film to reveal. Bacon does his usual good work, and there's a fine performance by Kathryn Erbe as his beleaguered wife, but when the suspense wanes there just isn't enough moving at the film's core.

It's hard not to like David Koepp, not to admire the proficiency behind most of his work, a fact obviously not lost on frequent collaborators like Spielberg and DePalma. "Be kind. Remember, this was two years of my life," he says to me as I leave our interview. It's an honest, quietly direct request, and, however mixed my response to his film, it makes me like him even more.