THE ONLY STOCK Washington character who does not appear in Allen Drury's new novel about the Senate is the Wily Lobbyist. This must have been an oversight, for all the rest are here: the Idealistic Young Senator, newly arrived in Washington; the Stalwart Political Wife, pregnant to add visible pathos to her plight; a whole roster of senators from th Wise Old Southern Committee Chairman to the Urban Black who offers advice on how to go along and get along; the Politically Ambitious Administrative Assistant; the Protective Secretary, the Washington Hostess. In the press gallery there's the Fatherly Wire Service Reporter who has seen senators come and go, the Ambitious Investigative Reporter who is torn by a conflict between journalistic "duty" and friendship, and the Bitchy Female Journalist for whom power is an aphrodisiac.

Anyone who has watched the Senate in operation could almost put names to the faces. But only almost , and therein lies the flaw in this novel. Even politicians and their entourages come in shades of gray. Drury's hero, Senator Mrk Coffin, is faced with a real shades of gray. Drury's hero, Senator Mrk Coffin, is faced with a real enough dilemma -- the degree to which a politician should compromise principle for political effectiveness -- but, by painting everything in black and white, Drury side-steps any serious consideration of it.

Mark Coffin, U.S.S. is the story of a liberal Stanford professor's first days as the junior senator from California. He is the son of a powerful conservative newspaper publisher, the son-in-law of the chairman of the Senate Armed Services Committee, and the political protege of the governor of California. Since he led the Democratic ticket in California, helping to deliver the state for the the party's presidential nominee, Senator Coffin arrives in Washington with the new president owing him a substantial political debt. Mark Coffin is also 32 and handsome, with an attractive savvy wife and two adoring small children. He is, in short, quite a politico-literary mouthful, one which taxes the digestion of any reader.

The new senator is immediately in the thick of things. He is asked to support the president's nominee for attorney general, a former district attorney from Los Angeles who has a reputation for being strong on law-and-order and rough on members of minority groups. Minutes later, Coffin is asked to back his father-in-law's bill authorizing a $10 billion increase in the Defense Department's budget. Like the white knight that he is, the new senator chooses to oppose both.

Thus Senator Coffin is plunged into the world of Capitol Hill -- its intrigues as well as the legislative process, with the latter greatly abbreviated to allow the story to reach its denouement about six weeks after the senator arrives in Washington.

As in all fairy tales, there is a moral. Idealistic young people must continue to come to Washington to fight, however futilely, for what they believe in, if the country is to keep going. In the words of an older senator, "You need the bumps and the bruises, the beliefs and the betrayals, before you begin to get a real inkling of what democracy is all about and how it operates."

It would be a happy, though rather boring, circumstance for all of us if Washington and the dance of legislation were as simple as Drury portrays them. What is utterly lacking in Mark Coffin, U.S.S . IS ANY SENSE OF THE COMPLEXITIES AND AMBIGUITIES OF A PLACE WHERE THERE IS NO HARD AND FAST TRUTH. Because Drury's characters are caricatures, with neither the greyness that envelopes most human motivation nor a convincing depth to their sorrow and anger, the book fails to deal honestly with Senator Coffin's dilemma. Drury's readers will learn something about Senate procedure but little about the nuances which are an important part of any political process.