"Flashpoint," a nominal political thriller that has nothing to do with "Flashdance," nor with much of anything else for that matter, begins in a ditch and ends in a sinkhole. Once or twice it gets up the energy and ambition to scale a hill of beans.

The picture, now at area theaters, opens with a jeep plunging into said ditch on a dark and rainy night in the desert near the Texas-Mexico border. This happened about two decades ago, we learn later, when two Border Patrol pals played by Kris Kristofferson and Treat Williams happen upon the largely buried jeep and discover its contents to be a rotted corpse, a high-powered rifle with a telescopic sight, and $800,000 in dusty cash. Kristofferson, as the rangy, practical one, wants to take the money, presumably from a long-forgotten robbery, and kiss the border patrol goodbye, but Williams plays one a' them ornery cusses who's got -- well, he's got "integrity," as Kristofferson says -- and he wants to get to the bottom of this. Not the ditch, the mystery.

Unfortunately for them both, the solution to the mystery dawns on the audience long before it dawns on the characters, who in Dennis Shryack and Michael Butler's bare-bones screenplay, keep behaving in sloppy, clucky ways. It doesn't occur to them that they're in over their aviator sunglasses until two of their fellow Border Patrollers are viciously murdered merely for having a couple of key telephone numbers in their possession.

The writers, and director William Tannen (a Madison Avenue grad who directed the star-studded commercial that introduced Diet Coke), try to dignify their desultory tale by linking it to the political crime of the century -- the one that occurred in 1963, when the jeep disappeared. But they don't let the characters make the link until the last frames of the film; it's used as a kind of dignifying exclamation point, and by that time, one's interest has been buried deeper than the jeep.

If you're going to make a conspiracy thriller in 1984 -- well, first of all, you're crazy, because the country has rarely seemed in a less paranoid and cynical mood (it may be optimistic hysteria, but it is optimistic). Second, you don't try yet another parlay on a JFK assassination conspiracy theory. You pick something contemporary, like the fundamentalist far right, or Citibank. It's also discouraging to realize about half an hour in that we're never going to leave this few square miles of desert for very long (it's Tucson, guest-hosting for Texas, where productions costs would have run higher), and neither Tannen nor cinematographer Peter Moss appear to have the ambition or the desire to turn the desert itself into a character. It was far more ominous and forbidding in "Them!," the early '50s screamer about giant ants. The Tangerine Dream musical score seems less arid than vapid.

Kristofferson and Williams never quite mesh into a team, but they both do about as much as can be done with the characters they play, whom we are to admire in spite of their grating slow-wittedness. The real victims of the film are Tess Harper and Jean Smart as a pair of telephone operators whose car breaks down and who are picked up by Kristofferson and Williams and then summarily dropped by the filmmakers. Smart plays too broadly as the tough one, but Harper's country-girl charm seems to have been transferred intact from the part she played in "Tender Mercies." It's too bad she is given virtually nothing to do.

Indeed, even a romance on the run deserves the decency of a fully developed scene or two. Instead, the screenwriters opt for another paean to male bonding. While in bed with Harper, Kristofferson recites an ode of appreciation to his swell, swell buddy-boy. "He's a real straight arrow; they don't make 'em like that anymore," Kristofferson babbles on. Of course, few audiences are so unhip that they won't be able to figure out from that kind of a speech what kind of fate awaits Williams. No, you can't be that noble in a paranoid fantasy and expect to make it to the end of the picture alive.

Rip Torn tosses off a few easy snarls as a corrupt sheriff named Wells (homage to Orson's "Touch of Evil," perchance?), and Kurtwood Smith stares down the whole desert as a vicious federal officer (FBI or CIA, we aren't told which, but in movies like this, it doesn't matter). Smith certainly does communicate the mind-set of a modern-day crypto-machismo (the kind of guy who wants to be in charge of security at rock concerts, or maybe secretary of defense), but the lines given him are just too painfully obvious, as when he confides to Kristofferson during a desert stakeout, "Every morning when I get up, I thank God for drugs and murder and perversion, because without them, we'd all be out of a job." Yeah, and Hollywood would go broke, too.

A tiny bit of film history is made with "Flashpoint"; cable viewers will be surprised to encounter the Home Box Office theme and logo on a great big theater screen. This picture is the first venture for HBO and something called Silver Screen Partners (released through the also newly arrived Tri-Star Pictures), but auspicious it is not.

Once the belated moment of revelation has come and gone, and Torn ties up a few (but by no means all) loose ends for Kristofferson and the audience, Kristofferson gets one of the lamest fade-out lines in motion picture history, a toothless threat on the order of "I'll be back and you'll be sorry." It's an appropriate way, though, for "Flashpoint" to sputter itself off of screen and out of mind.