HEAVEN AND HELL By John Jakes Harcourt Brace Jovanovich. 700 pp. $19.95

READING John Jakes' novel is a little bit like rooting for Oklahoma in college football -- you do so with the expectation that colorful newcomers will join forces with a roster of veteran superstars, crank up a juggernaut and head for a top spot in the national rankings. Which, when you think about it, makes Jakes the Barry Switzer of popular fiction (and Jakes has the added advantage of not having to play Nebraska at Lincoln).

Heaven and Hell, Jakes' latest novel (and the concluding volume of his best-selling North and South trilogy) continues the saga of two families, the Hazards and the Mains, in the wake of Appomattox as they try to pick up the shards of their lives that have been shattered by the Civil War.

Jakes has selected three themes for this concluding volume -- the travails of South Carolinians trying to cope with the aftermath of the war, Reconstruction and the advent of the Ku Klux Klan; the open political warfare (over the shape of the postwar peace) between the Republican Party and the unwanted president inherited in the wake of Lincoln's assassination; and the relentless pursuit of red Americans by white Americans for control of the American West.

Of the three, events in Washington work least well. The developments leading to the impeachment of President Andrew Johnson make for complicated history and political science, much less fiction. As a result, Jakes' characters occasionally end up conversing and musing in a style best described as early Agronsky and Company (as when Virgilia Hazard ponders the latest Congressional attempt to hamstring the president: "Stanton was Lincoln's appointee, not Johnson's . . . She thought there was a strong argument that Stanton was actually outside the Tenure of Office jurisdiction.")

Jakes is on more solid ground when he shifts the action out of Washington. The imposition and ultimate failure of Reconstruction in the South covers some well-traveled ground but Jakes manages to resift the historical information, meld it with his fictional characters and produce an informative and nicely crafted narrative (the one exception being Madeline Main's all too frequent "journal" entries directed to her dead husband, an intrusive dear-diary device that seems strained).

The action in South Carolina and Washington is secondary to the major venue, the American West. And it's here that Heaven and Hell sparkles, as Charles Main, late of the Confederate Army, tries to carve out a new beginning for himself and his infant son on the frontier, first with a black cavalry unit and ultimately as a scout for the Seventh Cavalry, the headstrong George A. Custer commanding. Jakes is particularly adept at capturing the splendid desolation of the untamed West, the mind-numbing isolation of duty with the frontier Army, and the unremitting brutality of the subjugation of the American Indian. His account of Custer's daybreak surprise attack on the Cheyennes encamped by the Washita River as seen through the eyes of Charles Main is hard-edged, capturing in vivid and unnerving detail one of the most controversial episodes in Custer's tempestuous career. It is the best reading (and writing) in the entire trilogy.

AS USUAL, it is Jakes' characters who propel the action. There are some promising new faces -- Willa Parker, actress, activist and Charles Main's love, stands out (though she lapses on one occasion into syrupy Miss America oratory that would make Bert Parks wince: "I like early mornings . . . I like the sight of children sleeping . . . ") -- but the newcomers have to compete for playing time with some admirable heavy hitters from prior volumes (the disillusioned Charles Main, the stoic George Hazard and the stalwart Madeline Main) as well as their villainous kin.

Ah, those villains. Longtime readers will be pleased that the odious Stanley and Isabel Hazard, who made a killing on Union Army war contracts during the Civil War, have now focused on greener postwar pastures. Isabel's venture capitalism knows no geographic (or ethical) bounds. In a later age, she'd have been a natural on Wall Street Week (Q: "What do you like in this Reconstruction market, Isabel?" A: "I'm taking a strong position in carpetbagging, Lou.")

It's also reassuring to note that Ashton Main, the high priestess of malevolence, hasn't lost a step (though losing a step would hardly faze Ashton inasmuch as verticality is hardly her strong suit). Speaking of lost steps, when we last encountered the loathesome Elkanah Bent, lifelong enemy of the Hazards and Mains, he was doing an involuntary Greg Louganis number off a high bluff above the James River and was presumed dead. Bent's back -- living proof that you can't keep a bad man down -- elevating crazed mayhem to an art form and providing some of the more chilling scenes in the book.

Having skillfully pulled these disparate themes and characters into a cohesive whole, Jakes is understandably hard-pressed to bring the saga and the trilogy to a neat conclusion -- Heaven and Hell doesn't end so much as it stops. But that's easily overlooked. Hey, even Oklahoma fumbles once in a while.

Rory Quirk, a Washington attorney, is a frequent contributor to Book World.