BOOK REVIEW / NOVEL : Charting a Friendship Through Secrets, Power and War : BROTHERS NO MORE, <i> by William F. Buckley Jr.</i> ; Doubleday; $23.95, 304 pages

The Cold War is over, and William F. Buckley Jr. has acknowledged that fact by writing his first novel that is not a spy thriller starring Blackford Oakes, the CIA’s puckish rejoinder to James Bond.

“Brothers No More” traces the tortured friendship of Danny O’Hara and Henry Chafee from the battlefields of World War II to those haunts of American political, journalistic and cultural power that Buckley knows so intimately.

O’Hara, a fictional grandson of President Franklin D. Roosevelt, covers up for Chafee when the latter panics during combat in Italy in 1944 and attempts suicide. It seems--and at this stage in O’Hara’s life, it may even be--a noble and generous act, but it subjects Chafee to a lifetime of emotional blackmail.

The two later room together at Yale. O’Hara keeps Chafee around because he needs occasional help getting out of scrapes--such as a French pimp’s attempt to take advantage of his casino debts on the Riviera--and Chafee’s gratitude is an unlimited bank account that he can draw upon. In turn, O’Hara is the sole witness to Chafee’s dogged efforts to rehabilitate himself by boxing and other tests of courage.

O’Hara falls in love with Chafee’s beautiful, devout sister, Caroline, and Chafee blesses their marriage despite growing doubts about his friend’s character. O’Hara eases into a top job in a hotel chain and condescends to his “plodding” brother-in-law, who becomes a foreign correspondent for Time magazine.

Handsome, vital and charming, O’Hara is halfway reminiscent of the Kennedys--he has their flash and faults without the compensating virtues. From the beginning, we see him cutting corners. He cheats on a French exam. He steals his mother’s diamond necklace. He embezzles millions from the hotel chain’s aged founder and defrauds his grandfather’s presidential library. He is guilty of flagrant adultery against Caroline and--in the case of the French pimp, who photographs him in a compromising position--murder.

The nerve and improvisational flair that made O’Hara a hero in his youth keep his ambitions afloat, but as he pursues a U.S. Senate seat he stoops to increasingly desperate expedients.

Meanwhile, Chafee, the “complete professional,” distinguishes himself at Time and finally exorcises his wartime ghosts in a nighttime encounter with a Viet Cong sniper. He remains chaste so long that he and others wonder whether he is gay, but he finally finds love with a snotty, liberal graduate student at Columbia School of Journalism who calls him a “quiet fascist creep.”

When O’Hara’s falling trajectory and Chafee’s rising one intersect, the results are lethal. In a typically witty Buckley touch, it’s French mystery novelist Georges Simenon, who, being interviewed by Chafee, unwittingly supplies the clue that uncovers O’Hara’s deepest secret.

Buckley, of course, is one of the godfathers of modern American conservatism: founder of the National Review, host of “Firing Line,” syndicated columnist. A snotty, liberal reviewer (like me) could read “Brothers No More” half facetiously as an allegory. O’Hara is the Democratic Party, squandering FDR’s New Deal legacy; Chafee is the Republicans, relying on faith and hard work to rebound from defeat and gain the moral and electoral high ground.

But not enough of the connections work--O’Hara is a libertine but hardly a liberal--and in any case, such a load of meaning is too much for a light and graceful entertainment like this to bear.

It’s more illuminating to note when Buckley really cares in “Brothers No More” and when he’s just going through the motions.

Sex? It’s not an abiding obsession, despite the novel’s many couplings. Sailing yachts? Yes. College dress codes? Maybe. Journalistic and scholarly ethics? Most definitely. Religion? One would expect so, given the tenor of Buckley’s writings from “God and Man at Yale” on, but his exemplar of saintliness, Caroline Chafee O’Hara, is too much the legless angel of Victorian fiction to come alive on these pages.

Indeed, although “Brothers No More” is a novel of character, Buckley’s true interest doesn’t seem to lie here, either. O’Hara succumbs to temptation with hardly a qualm, and his self-analysis is feeble. Chafee’s one failure (during which we are denied access to his mind) is an anomaly in an otherwise blameless life.

But when Chafee is in South Vietnam in 1963 and gets wind of the CIA-sponsored coup against President Ngo Dinh Diem, and stakes out the house in Saigon where Diem is trying to hide from his assassins, and the phone lines are burning up with consultations between Chafee, Time Publisher Henry Luce, chief of correspondents Richard Clurman, Foggy Bottom and the White House, the writing crackles with authority. Buckley is in his element here, doing what few novelists can do as well--and, not incidentally, back in the Cold War, still and always his favorite place.