In the final minutes, as the evidence against Kristin mounted, her adherents sat taller and her detractors sank deeper.

"I'll deal with Kristin my own way," iced J. R. The triumph dropped from her face, the frame froze, and the booing erupted.

"You like that?" stamped Lorraine Rose, a biofeedback therapist. "Weak," grouched her husband, model Joel Kaplan. Slumping back against the arm of the sofa, Rose said dourly, "This may be the last time we watch 'Dallas.'"

Rose and Kaplan, along with ceramic sculptor Barbara Mones and a handful of writer friends, spent at least 40 minutes before "Dallas" began last night marching one last time through the list of suspects. Kaplan, sporting a slightly misspelled yellow sweatshirt proclaiming "Doctor Elby Shot J. R." which he had made up at the end of last season, laboriously constructed the case against Sue Ellen's psychiatrist: It included unrequited love, a messianic urge to remove her oppressor and a somewhat contradictory inclination to hang the rap on her.

Mones, who after months of indoctrination was leaning toward Kaplan's theory, swapped sides just before the telecast began and sat through the final scene with a gentle malice afterthought.

All over America last night, millions of viewers, regular "Dallas" fans and the occasional user, craned from armchairs, carpets, barstools and late-night offices to see which of the variously low-life denizens of the successful soap opera tried to give ol' J. R. his comeuppance.

And even those who had settled on sloe-eyed sister Kristin beforehand were stunned by her final bombshell -- that she is pregnant by good ol' J. R. It was, after all, a brilliant piece of preventive medicine: sort of defense by descendant.

"Dallas" may be thought of by the incognoscenti as a kind of redneck blue-collar phenomenon. But it is intriguingly likely that the group of young professionals at Mones' Kensington home last night represented a real trend in '80s America -- vicarious rascality in the face of the Moralizing Majority.

The coming attractions for next week's show skipped right past Kristin and her great expectation back to the everyday struggle between J. R. and Bobby Ewing for control of the Ewing Oil Co. and the power it represents. That, it can safely be assumed, will not interest so many people. Nobody takes odds in Vegas about oil refineries.

"It looks like they're reaching for a whole new audience," grimaced Kaplan, picking idly at the Elby on his chest. "Must be the Reagan people."