WARD JUST's new novel, like the eight works of fiction and nonfiction that preceded it, is preoccupied with two subjects: Washington and Vietnam, which happen also to be where Just spent most of his career as a journalist. Its characters, like those in his previous work, occupy the upper and upper-middle tiers of the power structure; its settings are the corridors and salons of power that they inhabit; its themes, though addressed from various directions and angles, involve the ways in which power is exercised and the moral dilemmas it poses.

Beyond any doubt, In the City of Fear is Just's most ambitious attempt to grapple with these matters. It is not a work of great length, but it embraces a large cast of characters and a formidable array of themes and variations--too large and too formidable, in fact, for the book to succeed as fiction. In the City of Fear is a novel of ideas and opinions; given that its author is Just, these are usually interesting and always elegantly stated. But its structure is oddly misshapen and uninviting, its characters are less appealing than Just appears to believe them to be, it contains too much brittle talk, and its doggedly solemn atmosphere is ultimately exhausting. There's much in the book to admire, but little in it to like.

Though the novel moves back and forth in time, from the first pregnant moments of American involvement in Vietnam to the final hours of indecision and withdrawal, its principal activity takes place during the time of the nation's most intense and divisive commitment there. Its main characters are Piatt Warden, an ambitious young representative from Illinois; his wife, Marina, "indisputably a woman who knew the score"; and Sam Joyce, a colonel in the Army who "had gone to the war in the beginning and had stayed almost until its end," and who has been Marina's lover for many years. They and their closest friends, among whom are an influential journalist and an official of the Central Intelligence Agency, reside in a tiny corner of Georgetown that they know as Shakerville from "their half-joking description of themselves in the old days, 'movers and shakers.' " It is a dinner party in Shakerville that provides the core around which the novel is constructed, a party at which many hard truths are painfully exposed.

As the party begins, Marina reflects upon the mood of the day: "Lately Washington had come to seem to her like a Potemkin village, a facade maintained for the sake of the authorities, a city nervously preserving its good grooming -- a gallant mustache, a confident pompadour -- for the Crown, on those rare occasions when the Royal Train took to the boulevards. Washington now was like a family suffering terrible, unspeakable illness. It was an illness that could not be described to outsiders, so the family, once so cocky, was now subdued and defensive. It was family trouble, and they were all part of it." The dinner party is, in microcosm, a gathering of that family -- a domestic battle mirroring the real war being fought several worlds away.

Though a great deal is going on in this little battle, the central struggle is for Piatt Warden's soul. He is "a shrewd legislator, an insider; an insider's insider, rated as one of the ten or fifteen most effective legislators in the House," and he has cautiously, carefully stayed on the fence in the Vietnam debate -- a position that makes him the subject of intense wooing by the White House, the occupant of which Just brilliantly portrays. As the evening wears on, as whiskey and fatigue do their work on the diners' inhibitions, the full panoply of moral and political questions confronting Piatt -- as well as Washington itself -- is gradually, remorselessly brought to light. It is a process that leaves only one participant on fully defensible moral terrain: Sam Joyce, the good soldier, drawn back to Vietnam over and again not out of love for combat but out of loyalty to his fellow soldiers -- his fellow men.

Sam Joyce is the novel's central character, if indeed it can be said to have one, and when he first appears in it he establishes its central metaphor. His war is over now and he is in a Washington hospital, the victim of a corrosive disease: "A stupid army has invaded him, an army with no imagination and led by clumsy captains. It followed a scorched-earth policy, advancing on all fronts simultaneously, its commander in chief as slow-witted as Custer or the butcher Foch." The metaphor -- disease eating up a man, war devouring a nation -- is painfully obvious, and symptomatic of the difficulty Just creates for himself in the novel: he is so intent on proving his thematic points that he takes the life right out of it. In the City of Fear is more successful as editorial commentary than as fiction.

A revealing case in point is its conclusion. A character named Dennis McDonough, who to this point has been a distant and mysterious figure, suddenly emerges from the mists of the past to assume the novel's full thematic burden. He was, in the very early years of the Vietnam misadventure, a middle-level official in the National Security Council who had written a memorandum opposing further involvement: "he had gone on record; a brave act." Now, in a flashback to those years, we learn the gruesome details of his accidental death and are urged to contemplate its meaning:

"What did we know best? What had we lost? What did we believe, except that we were on the frontier of a brilliant adventure that nothing could halt or foreclose? As to the adventure itself, there would be portents. Was there something after all to be made of this death, so random and unprecedented?"

Of course: the death of Dennis McDonough presages the deaths to follow in Vietnam, and when his wife sees a film of the fatal accident broadcast on television, the "living-room war" is prefigured. That all of this is symbolically accurate goes without saying, but it is also numbingly obvious. Just is a writer of considerable sophistication, but in his earnest desire to teach the lesson of Vietnam -- and the lesson that moral commitment must not be shied away from -- he resorts to a clumsy apparatus. From the first page of In the City of Fear to the last, you can see the machinery cranking. The novel has many fine moments, but it is simply too programmatic to sustain attention or genuine interest.