Given that this is a Linday Lohan movie, you might expect the answer to be the bartender or the drug-dealer—or even the assistant’s mother. (Or maybe to be a story of self-destruction.) But “I Know Who Killed Me” is the sort of picture that has nothing whatsoever to do with real life. Its true ancestors are the lurid grande dame exercises in Grand Guignol from the 1960s—wild, operatic, implausible flicks like “Hush…Hush, Sweet Charlotte.” But those movies were fun; this sleazy, silly thriller is so bad it doesn’t even seem to realize it’s unadulterated kitsch.

The plot is a dark doppelganger mystery. High school sweetie Aubrey Fleming (Lohan) is abducted by a serial killer who’s already dismembered a classmate. When she’s discovered with a hand and leg removed, she claims she’s not Aubrey but Dakota Moss, a stripper recently moved to town after tough life (crack-addict mother and all that goes with it). Aubrey’s parents (Neal McDonough and Julia Ormond) think she’s confused, and the FBI agents on the case (Garcelle Beauvais-Nilon and Spencer Garrett) believe that she’s suffering from delusions and assuming the role of a character in one of the stories she’s written. But with the help of her quarterback boyfriend (Brian Geraghty), she’s determined to unravel the riddle of her identity and find the still-missing Aubrey.

The script by Jeff Hammond might have worked in one of two ways. One would have been to go a knowingly ridiculous, campy route (it worked for “Charlotte” and “What Ever Happened to Baby Jane?”) The other would have been to come up with a plausible answer to the puzzle it’s established. But “I Know Who Killed Me” does neither. It proceeds like a serious thriller, but becomes more and more preposterous as it goes along. The resolution of the “doubling” plot is as absurd as the Internet investigation Aubrey/Dakota does to solve it. But that pales beside the revelation of the killer’s identity. To be honest, I suspected early on—within twenty minutes or so, when the precise wounds inflicted on the victims were rather graphically depicted—who the culprit might be. But I immediately rejected the idea because it was so outlandish. Unfortunately, that apparently wasn’t the case for Hammond, or for director Chris Silvertson, who chose to exacerbates its nonsensical quality by staging the big denouement as garishly as possible. But not in the tongue-in-cheek fashion that might have saved it.

No actor could have sold this stuff, but it’s certainly beyond Lohan’s rudimentary talents. She gets to suffer ostentatiously, and also to scream while tied down to one of those ancient gurneys these prefabricated “Saw”-inspired serial killers seem always to have on hand, to do repeated flashback strip-tease sequences in revealing outfits, and even to have a session in bed with the quarterback. But her brooding and brusque dialogue delivery has all the punch of a high-school drama production. When trying to act studious she’s completely unconvincing, and elsewhere she can’t pull off the incompatible sides of Aubrey as Hammond’s sketched her (at one point she demurely refuses her boyfriend’s advances, but at another she’s an oversexed slut toying with the family’s oily gardener). She’s better as Dakota, to whose nasty, world-wise personality she seems more temperamentally suited, but even there the performance is all surface effect. As for the rest of the cast, it’s to their credit that they get through the movie without bursting out laughing. One has to commiserate especially with one Thomas Tofel—and when you see the movie you’ll know why. On the non-human side, the picture features perhaps the ugliest cat ever to grace the screen.

From the technical perspective, the movie’s just okay. John R. Leonetti’s cinematography emphasizes dankness and a forbidding atmosphere, though the emphasis on azure blues in the color composition and owls as symbols is excessive. Lawrence Jordan’s editing could have used some prodding; the picture overstays its welcome by fifteen minutes or so. And John McNeely’s score does its job, though without much distinction.

Given the way it’s turned out, it’s understandable that “I Know Who Killed Me” didn’t screen for press. The real mistake lies in screening it for everybody else.