John Flynn's crisp, laconic direction and evocative use of Southern Texas locations - the San Antonio area, with particularly effective, sinister excursions to border towns like Del Rio - transorm "Rolling Thunder," now at area theaters, into a more distinctive exploitation movie than it deserves to be. The screenplay, which originated with Paul Schrader, the writer of "Taxi Driver," is miserably vicious, a hybrid of "The Wild Bunch" and "Death Wish" in which a returning P.O.W., an Air Force major who spent eight years imprisoned in North Vietnam, sets out to massacre a gang of hoodlums who break into his home, shove his right hand down a churning garbage disposal and shoot his wife and son.

The premise is twisted in a way that could serve as a textbooks example of pornographic violence. All the major's ordeals - physical and emotional, as a prisoner and a returning serviceman and family man - become pretexts for kinked-up, brutal sensations and a final orgiastic shooting spree.

There's no point in responding to the hero's situation with ordinary sympathy or human interest, because these amount to sucker's responses in this context. Flynn directs the homecoming encounters between William Devane as the major, Hordon Gerler as his son and Lisa Richards as his wife, who has become romantically involved with another man, with such admirable stillness and concentration that one could be fooled into believing that the film intends to deal with his readjustment problems conscientiously. In retrospect, one may recall this as the neatest single illusion in the picture and wish John Flynn a more appropriate subject for stylistic concentration the next time around.

it doesn't take long to discover that the humanistic murmurs are setting up nihilistic knock-out punches. Bringing on the murderers spares a screenwriter the drudgery of trying to resolve the estrangement between the major and his wife. At the same time it's presumed to give a melodramatic warrior a "mission" worthy of his training and value system. Yet there's no conviction behind this mission of vengeance, no sense of values that might deserve to be protected or offenses that might deserve to be punished.

On the contrary, the hero and a fellow P.O.W. who joins him, played by Tommy Lee Jones, are justified on the basis of professionalism rather than motive. We're supposed to accept the platitude that they're emotionally dead and have been since their capture during the war. The major has become a stranger to his family, and while he's offered a girl friend who might be some consolation - Linda Haynes, who resembles a careworn Tuesday Weld, makes an appealing impression as a cocktail waitress whose down-to-earth aspirations and apprehensions correspond to the audience's - he must reject her, or else miss the climactic shootout.

The major's comrade leaves a household conceived as the meanest of lower middle-class sancturaries, a haven for prattling women and unheroic men. In its simultaneous contempt for the homefronts the heroes ostensibly march out to avenge or protect and for the scummy adversaries they'll face, the movie exposes an emotional and moral blackout far more genuine than the perfunctory daze ascribed to Devane and Jones, both very capable actors. This picture was conceived by someone - presumably Schrader - who glorifies violence, yet only responds to it as a transcendant, abstract pictorial spectacle, an esthetic thrill, like the nomcombatants who derive more satisfaction from combat than professional soldiers.

There are some exceedingly ugly notions in "Rolling Thunder," and they're never mitigated by the kind of character exploration and embiguity that strengthened "Taxi Drive." For example, the major is depicted recalling nightmarish scenes of torture and then reenacting some of those scenes, with a hint of of masochistic gratification. His severed hand is replaced by a prosthetic device that becomes even better than a hand for the purposes of this story, because he can file the to a point and use it as a deadly weapon.

The big showndown self-sconsciously justaposes sex and violence. The setting is a Mexican bordello, so naked actresses scurry about trying to stay out of the line of fire while the actors pretend to have it out. Speaking of having it out, Jones is depicted being undressed by a whore seconds before the shooting starts, and he comes out of her room with an automatic rifle in one hand while zipping up his fly with the other. "Rolling Thunder" is undoubtedly Spawn of Peckinpah, but some of its kinkier wrinkles might shock the originator himself.