If "Memento" were some sort of literary deconstruction about how, in detective stories, the quest is more important to the detective than solving the mystery, it would probably get top marks. You can watch Pearce tracking down his incomplete information, not even knowing who he's going after or even why and come up with a whole riff on the existential subtext of detective fiction, how it functions as a metaphor for going through the motions of everyday life. (The French will have a field day with it.)

But all that is cold comfort to an audience that's been promised a mystery with a solution. There is a solution, of sorts, but one that feels like a cheat because instead of being solved, the mystery evaporates before our eyes.

"Memento" might have postponed being revealed as a cold exercise if the filmmakers had cast someone other than Guy Pearce in the lead. All I could get from Pearce in "L.A. Confidential" was a stiff actor playing a dullard straight-arrow whose conflicts didn't go deep enough to seem interesting. Here, done up in a shock of spiky, dyed-blond hair and various creepy tattoos (designed, it would appear, after Robert De Niro in "Cape Fear"), he's a blank, not even a man tormentedly trying to recover his past. He's so affectless that being a blank seems what he aspires to. The loss of short-term memory is his fulfillment.

It's curious that after laying out such a meticulous puzzle, Christopher Nolan introduces the booby trap that detonates the surrounding material, namely Stephen Tobolowsky and Harriet Sansom Harris as the couple from an insurance investigation that haunts Pearce. Tobolowsky is a man who's unable to continue working when he develops the same short-term memory loss that Pearce eventually suffers from.

Pearce, working to save his company money, prevents Tobolowsky from getting covered for his ailment and the poor man's wife is left wondering whether her husband is faking. Harris captures the escalating desperation of someone trying to hold onto a normal life as the floor is kicked out from beneath her, and Tobolowsky gives perhaps his best performance. He's one of those actors whose face you know even if you don't recognize his name. He was the jeweler who deflects Annette Bening's advances in the most gentlemanly manner possible in "The Grifters"; he was one of the CBS lawyers working to kill Russell Crowe's "60 Minutes" appearance in "The Insider"; and he was Ned Ryerson, the insurance agent who kept pestering former classmate Bill Murray in "Groundhog Day."

With the fringe of hair around his bald head, and his big eyes and tall build, Tobolowsky could be Homer Simpson's basketball-playing cousin. He plays this role with the calm of a man who has entered the serenity of dementia; the lost, benign little smile on his face becomes more heartrending as the movie goes on. Whenever Harris or Tobolowsky come on-screen they stop "Memento" dead in its clever tracks. You want to tell Nolan to stop all the po-mo deconstructive game playing and pay attention to the two human beings in front of him.

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