In Spike Jonze and Charlie Kaufman's ingeniously idiosyncratic showbiz semi-farce "Adaptation" there is a running gag about a typically bogus Hollywood-thriller screenplay called "The 3," in which a preposterous, nonsensical twist ending reveals the three main characters to be different personalities in a schizophrenic's mind.

In this week's "The Butterfly Effect," a superficially chilling high-concept horror movie full of paradox-packed time-loop contortions, the entire plot depends on just such cursory twists, none of which stand up to much intellectual scrutiny.

Stoner-comedy staple Ashton Kutcher -- who, like a young Keanu Reeves, is hard to take seriously in any non-stoner role -- stars as Evan Treborn, a double-psychology major (snicker, snicker) working on a memory assimilation thesis inspired by blackouts he suffered as a child during several traumatic events.

In the first half of the movie, the shock-value-driven writing-directing team of Eric Bress and J. Mackye Gruber (scripters of "Final Destination 2") inflict on the audience each of these episodes from Evan's life, distastefully alluding to kiddie porn, barbequed pet dogs and a mailbox bomb that kills a young mother and -- just to make the incident as ghastly as possible -- her baby too.

When adult Evan is later shaken by the suicide of a childhood girlfriend (Amy Smart), he inadvertently discovers he can reorder the past by re-reading the journals he kept as part of his youthful psychotherapy. The memories induced thrust him back into the empty moments of his blackouts and allow him to change related events. His ability to reach from the present into his own body in the past (through space-warping shaky-cam effects) ends up being the cause of the blackouts in the first place.

But with each timeline alteration comes something unexpectedly terrible in the present, and soon he's tapping the journals from every missing moment of his childhood, looking for another chance to fiddle with history and try to set things right.

It's a viable concept with many Ray Bradbury-inspired possibilities, but Bress and Gruber obviously didn't examine their plot twists for plot holes. Some of the present-day horrors are far-fetched (in a rich frat-boy timeline he ends up in prison, awaiting trial for a first-offense killing when he could easily plead self-defense and make bail).

Some of the changes made in the past have ridiculously little effect in the future (an act of self-mutilation that would have sent the kid into much more serious therapy changes nothing in the future except giving Evan a pair of small physical scars). Others result in Evan's life changing drastically around him and involve a painful flood of new memories forming -- yet inexplicably his personality, psyche, and hairstyle always remain the same.

Some of this nonsense can be dismissed as inevitable incongruities intrinsic to the time-travel genre. But there's no consistency to the films internal logic -- a fact that is in evidence most blatantly when one of Evan's jumps results in new memories flooding into his mind from someone else's life -- not because of some strange twist of science fiction, but for the sake of narrative shorthand.

I could spend paragraphs pointing out gaffes in "The Butterfly Effect." But its dozens of elemental inconsistencies might have been easier to swallow if the film had actors of a higher caliber than these lightweight stars hired more for their demographic appeal (Kutcher hosts his own cruel practical jokes show on MTV) than their talent.

Kutcher does have a gift for playing dumb in comedies. His scene stealing in last month's "Cheaper by the Dozen" -- ironically as a talentless, self-serious actor -- is that movie's only reliable source of laughs. But he doesn't have the gravitas to get audiences in his corner as the hero of a wannabe-brain-twisting psychological sci-fi thriller. Even the film's better actors -- like Melora Walters ("Magnolia") as Evan's mom and Eric Stoltz as the girl's abusive pervert pop -- are poorly chosen for their roles.

All this adds up to an incontrovertible lack of substance and cohesion that -- not unlike the mock shocker in "Adaptation" -- obviously enthralled shallow studio executives and probably won't register with less demanding moviegoers. But it will drive to distraction anyone who expects not just twists, but smart twists.

For a far more daring and novel approach to a similar concept, rent 2001's eerie, oddball underground hit "Donnie Darko."