Directed by Gary Fleder, 2002 (Color, 9:5, Surround, 35′/100′)
Starring Gary Sinise, Madeleine Stowe, and Vincent d’Onofrio

If you’re going to watch “Impostor,” watch the 37-minute version. Not even heavy-handed film direction can strangle Philip K. Dick’s fascinating story idea in half an hour. To smother a story this grim, paranoid, and thought-provoking, you have to throw in an hour-long chase scene too.

The half-hour cut of “Impostor” toys with questions about the nature of identity and knowledge. What does it mean to say that you are who you are? And how do you know, anyway? Do you know things because you understand them? Or do you know things because someone else said so? What’s it like to live someplace that only cares about questions like these as a matter of homeland security? And what if the only answers to these questions came from technicians, bureaucrats, and the gizmos engineers have built?

Unfortunately, even the short film brings up a few irrelevant questions, like why would you want to use slow-motion photography every time you think the audience should notice something? Why would you want your protagonists to be so ill-mannered that they demand to know if they’ve been introduced, not once, but twice, when a stranger speaks to them? Why would you want your antagonist to be so blatantly sadistic that the audience might believe your story is about depravity rather than paranoia?

We may never know the answers to the last set of questions, but the answers to the first set of questions are just as relevant now as they were when Philip K. Dick asked them back in the 1950s. Good science-fiction stories are like that. Because they don’t mention things like the Red Scare or the War on Terrorism they can get to the heart of the matter and talk about things like paranoia, people, and the social institutions that control how people think.

If only the filmmakers had been more concerned with these matters, and less concerned with flashy camera tricks and overblown characterization, then “Impostor” could have been the movie it wanted to be — wickedly entertaining and relevant — instead of what it turned out to be — clumsy and overly long.